Monarch butterfly

Monarch butterfly
Monarch butterfly ( Danaus plexippus )
Systematics
Order : Butterflies (Lepidoptera) Family : Noble butterfly (Nymphalidae) Subfamily : Danainae Tribe : Danaini Genre : Danaus Type : Monarch butterfly
Scientific name
Danaus plexippus
( Linnaeus , 1758)

The monarch butterfly ( Danaus plexippus ) or American monarch is a striking orange and black drawn butterfly (day butterfly ) from the family of the noble butterfly (Nymphalidae). It is widespread in America and spread across the South Pacific to Australia in the 18th century. The monarch butterfly is the best-studied butterfly in North America and a famous migratory butterfly . Individual animals cover up to 3,600 kilometers on hikes in North America in autumn. The eastern population in North America winters with several 100 million animals on a few hectares in the Mexican Sierra Nevada .

In the years from around 2010 onwards, the overwintering population collapsed drastically, the area used was also only a fraction; The arrival of the moths in Mexico was delayed by three weeks in 2013/14.

A significantly smaller western population overwinters along the Pacific coast in California.

features

butterfly

Males with clearly visible scented pouches

D. plexippus f. nivosus

The monarch butterflies have wings with an orange base color and black and white markings. The wing veins and their edges are black. On the black wing tips they have two rows of white to cream colored spots. Two rows of small white dots run on the black bands on the outer edge of the wing. The base color of the underside of the wings is lighter, especially on the hind wings. The black body has white spots on the head and thorax and three to four thin white rings on the abdomen. The size of the moths varies greatly, the average fore wing length is 47 to 50 millimeters.

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  ♂

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The males are usually smaller than the females and have a black pouch filled with scented scales on the second vein of the hind wings , which is formed from the pupa after hatching. At this point, the wing and the wing vein running next to it is swollen. The males have showy gray tufts of hair on the abdomen. These play an important role in pairing and each consist of about 400 hairs 2.1 millimeters long and 10 micrometers thick that sprout from the last third of the tufts of hair that can be turned out. The tufts of hair, with only one type of hair, and the scented pockets, a typical feature of the Danaini tribe , are greatly reduced compared to other species of the genus and the tribe.

The female moths have an overall lighter basic color, with the margins along the veins wider and both darker in color. In the very rare form D. plexippus f. nivosus , which is inherited as an autosomal recessive trait, all wing areas are greyish-white that are usually orange. The form has been seen everywhere (America, Australia, Indonesia) and is very rare except for Hawaii . On the Hawaiian island of O'ahu of the moths are found in this form up to 10 percent.

The wings and the entire body including the legs are covered with scales except for the compound eyes . 900,000 to 1.5 million scales of different shapes, ranging from narrow scales of different lengths with up to two points to oval shapes with up to three points, cover the wings. The narrow and long scales on the edge of the wing resemble hair and form the wing fringes. Scales of different shapes are interspersed with hair on the head and thorax. On the legs, all scales have the same elongated shape with two prongs.

egg

Egg (from Samuel Hubbard Scudder's Butterflies )

Freshly laid eggs are creamy white, and within three to four days they turn dark gray. An egg weighs on average 0.54 milligrams, is about 1.2 millimeters long and has a diameter of about 0.87 millimeters (average values ​​measured on 55 eggs). About 22 ribs, some of them branched, run along the surface. About 32 smaller ribs run across it, which form small cells with the longitudinal ribs. At the ends of the egg, the cells formed by the ribs become irregular and smaller and smaller, to finally merge into the micropyle at the top , through which the egg caterpillar later hatches.

Caterpillar

A last instar caterpillar feeds on Asclepias incarnata in Pennsylvania

The egg caterpillars have a black, shiny head and a light gray-white body. After the first moult, the caterpillars take on their typical white - black - yellow band pattern of horizontal stripes. The width of the individual colors can vary depending on the geographical region; in the Antilles, for example, the caterpillars are almost black. In the second larval stage, the fleshy appendages typical of the Danani tribes, two on the thorax (segment 2) and two on the anal segment (segment 11), are visible. All larval stages can be distinguished on the basis of features on the head and metathorax .

Doll

Doll with gold patch and ribbon

The caterpillar pupates in a squat-looking tumbled pupa , which is initially light green and later turns dark green. The skin of the doll, which appears slightly transparent, is reminiscent of jade . There are several small and a few larger golden dots on the pupa, on the abdomen the dots form a continuous band, which is accompanied by a black band downwards. Yellowish or whitish forms that are an adaptation to a different ambient color occur rarely.

Mimicry and similar types

Many species of the genus Danaus are similar to the monarch butterfly, with some species it forms Müllerian mimicry rings . Müllerian and Batesian mimicry are also known together with species of other genera.

• Danaus erippus is the sibling of D. plexippus and is distributed south of the Amazon in South America. It was previously considered a subspecies and is now accepted as a species based on genetic research. The moth is darker than D. plexippus and has a white spot on the brown background of cell 3 at the edge of the black outer band. This white spot occursonly very rarelyin D. plexippus . D. erippus has a similar migratory behavior as D. plexippus , but this has only been poorly researched. In the months of March to April, autumn in the southern hemisphere, northward migrations were observed in Argentina and wintering quarters are known from the province of Chaco in the north of the country. The latitude of D. erippus' wintering area in northern Argentinacorresponds to that of D. plexippus in the northern hemisphere.

• Danaus gilippus is in English as Queen ( Queen called) and replaced the monarch butterfly mostly in Florida ( D. gilippus berenice ) and the southwestern United States ( D. gilippus strigosus ). In the south-east it is brownish and in the south-west it is lighter in color. The species isvery similar tothe African monarch ( Danaus chrysippus ) and can be considered either a sister species or a subspecies thereof in the New World. The overall distribution extends over large parts of South America.
• Danaus cleophile has a small distribution area in Hispaniola and Jamaica , where it occurs together with the monarch butterfly. It differs from the monarch butterfly by yellow instead of white spots in the apical and subapical regions.
• Limenitis archippus ( Cramer 1775) is called Viceroy ( Viceroy )in Englishand is also a sometimes poisonous butterfly from the subfamily of the kingfishers (Limenitidinae) in the noblebutterflyfamily. It is common in North America, from the east coast of the United States to the Northwest Territories of Canada in the northwest, along the eastern edge of the Cascade Range and the Sierra Nevada south to central Mexico. The orange subspecies Limenitis archippus archippus developed a signal normalization (Müllerian mimicry) with Danaus plexippus in the northern distribution area. In areas where the monarch rarely occurs, in the southwest and southeast (Georgia and Florida), the brown subspecies Limenitis archippus floridensis developed a signal normalization with Danaus gilippus berenice . L. archippus is very similar in size and color to the monarch butterfly, but can be distinguished from it by an additional black stripe in the post-disk region on the hind wing.

• Danaus genutia ( Cramer 1779) occurs in Southeast Asia, from India via the Philippines to northwest Australia and, together with the monarch, develops Müllerian mimicry.

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  Danaus gilippus berenice

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  Limenitis archippus

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  Danaus genutia

Occurrence

habitat

The typical habitats of the monarch butterfly are open wasteland and ruderal areas , on which the food plants of the caterpillars thrive in abundance. The largest population density of the monarch butterfly in North America is in the area of ​​the Great Lakes , where many silk plants ( Asclepias ) grow. Although the moth is more of an inhabitant of the valleys, it rises up to 1500 meters in Guyana and up to 2000 meters in Central America .

Spread and spread

The moth is native to North America and northern South America. The northern distribution ends around the 50th parallel in southern Canada , which also roughly corresponds to the northern distribution limit of the silk plants. The distribution extends through the entire USA, Mexico, the Caribbean and Central America to the northern edge of the Amazon ( Venezuela , Peru , Colombia , Ecuador including the Galapagos Islands , Brazil , Guyana , Suriname and French Guiana ). The species D. erippus , which was previously classified as a subspecies, lives further south .

In the 18th century the moth expanded its range continuously and became native to Hawaii in 1840 . In the following three decades it spread over the islands of the South Pacific ( Karolinen (1857), Tahiti , Tonga (1868) and Samoa (1876)). In 1870 he was seen on Lord Howe Island and a year later in Australia ( Queensland 1870, Melbourne 1872). The monarch butterfly is common in Eastern Australia , while it is occasionally seen in other parts of the continent and in Tasmania . From the islands of the South Pacific, it has spread east across the Solomon Islands , New Guinea , Java , Borneo and Sumatra .

The first sightings of monarch butterflies in New Zealand are said to have taken place in 1840, but this was not documented until 38 years later. The moths allegedly captured and prepared at the time can no longer be found today. At that time it was believed that the moths were endemic to New Zealand, as the Māori supposedly have a traditional name for the moths (kâkãhu). It is now believed, however, that it was used to describe a similar looking butterfly. The first reliable report of monarch butterflies dates back to 1868.

To date, New Caledonia (1881), Marquesas (1883) Fiji , Micronesia , Melanesia , Réunion , Polynesia , Sulawesi (1873, 1981), the Norfolk Island , the Moluccas , the Philippines , Taiwan , southern China and Mauritius have also been settled in Asia and Oceania , where it disappeared again in Borneo, the Philippines and southern China.

Its spread in the Pacific region was likely man-made. White settlers brought silk plants, especially the Indian milkweed ( Asclepias curassavica ), to the islands of the South Pacific, on which they were not previously native. They planted them in their gardens, and there are reports of pillows and mattresses being filled with dried silk plants. From this some seeds could have found their way into nature. After the food plants were in place, the animals were able to survive and spread on the islands. It is not known whether the animals, which can fly several thousand kilometers, were on board ships or even flew to the islands. In the Bay of San Francisco , however, it is not uncommon for small groups of hibernating butterflies to gather on ships. It was also observed how moths land on moving ships. The long diapause also enables wide distribution.

Distribution of Gomphocarpus fruticosus on Faial

The monarch butterfly is now also native to the Azores , Madeira and the Canaries . The first sightings in the Azores, where the butterflies are called “Feiticeiras” (little witches), date back to 1864 (on the islands of Flores and Ilha do Faial ). The moths appear again and again, usually only for a short time a year and have flown away heavily, that is, faded and with damaged wings, which indicates an immigration from North America. There was only a proven breeding success in 1999. In the Azores, the species Gomphocarpus fruticosus , which occurs only in a few locations and in small numbers, is used as a food plant, which - as long as no other plants are added, such as on the Canary Islands and Madeira - severely limits the population size. The other silk plant found in the Azores , Araujia sericifera , has not yet been accepted. In the Canaries the islands of Tenerife , Gran Canaria , La Palma , La Gomera , El Hierro , Lanzarote and Fuerteventura are populated. The caterpillar feeds mainly on Asclepias curassavica , but also on Gomphocarpus fruticosus .

In Europe, the monarch butterfly was indigenous to southern Spain ( Málaga ) together with the African monarch ( Danaus chrysippus ) for several years in the 1980s . In the 1990s it probably disappeared together with the related species due to an unfavorable climate. Since 1997 the monarch butterfly has been down to earth again along the coast of Andalusia , often on the same plants as the African monarch, which was down to earth a few years earlier. Although several eggs of both species are often laid on one plant, no competition for the food plants could be established. In Portugal , southern France and Corsica , the monarch butterfly occasionally occurs as a migrant butterfly.

When monarch butterflies are drifted from North America in strong winds, they can sometimes be found on the coasts of the British Isles and Norway. Butterflies blown over the sea by storms are repeatedly observed from ships, as the following report shows:

I was a deck boy on the MV Laguna on a voyage from Liverpool to New York during September 1944. It was a convoy seven days out of Liverpool when order was given to scatter and make for New York without escort. This was due to the imminence of a hurricane in the path of the convoy. We encountered the edge of the hurricane and soon afterwards steamed into fair weather and blue skies. We were then 5 days or 1000 miles from New York when we ran through a massive swarm of monarch butterflies. I remember standing on deck watching this mass of colorful creatures fluttering around the ship's rigging. On arrival in New York I learned that the hurricane had turned westward, crossing Long Island, NY

“ I was a deckhand on the MV Laguna on a voyage from Liverpool to New York in September 1944. Seven days after leaving Liverpool, the convoy was instructed to split up and continue to New York alone. The reason was a huge hurricane on the route of the convoy. We encountered the edge of the hurricane and soon after steamed into good weather with blue skies. When we came across a huge flock of monarch butterflies, we were five days or 1000 miles from New York. I remember standing on deck and watching the multitudes of colorful animals that flew around the rigging . Upon arriving in New York, I learned that the hurricane had turned west and was moving over Long Island. "

- Vincent Varey, Stockport, England

Today's distribution of the monarch butterfly (orange), formerly populated areas (light orange) and dates of the first sighting

Columbus hypothesis

The lepidopterologist Richard Irwin Vane-Wright published the Columbus Hypothesis in 1993, in which he assumed that the monarch butterfly only multiplied and spread strongly in North America after the colonization of America by European settlers. The heavy deforestation is said to have created the prerequisites for the migratory movements of the moths, as many cleared areas were created on which the food plants of the caterpillars could spread very strongly. This is said to have led to such a strong growth in the butterfly population that the animals have spread over large areas of the temperate zones. Since the moths do not migrate or only migrate very little in other parts of the world, their migratory behavior is said to have developed only after the large spread across the Pacific. He also states that there are no reports of the migrations from before 1865.

The hypothesis no longer plays a role in research today. One of the arguments against them is that the sense of direction based on the sun and the earth's magnetic field should have developed within 200 years, which is extremely unlikely. In addition, the butterfly researchers Zalucki and Clarke have shown that only three places were necessary for the spread in the Pacific region so that the monarch butterfly could spread over the island groups. This could easily have happened unnoticed and inadvertently through human activity.

Way of life

A caterpillar in the second instar has eaten typical holes in a leaf. The fleshy appendages are already recognizable

Monarch butterflies mating

Female monarch butterfly laying eggs

Larvae

Before hatching from the egg, the black head of the egg caterpillar becomes visible behind the semi-transparent egg shell. The caterpillar bites an opening into the micropyle within a few hours. In doing so, she repeatedly takes breaks and leaves the egg shell after the opening has reached the size of her head. The majority of the caterpillars only eat parts of the egg shell, few eat the entire egg shell or only nibble off the opening necessary for hatching and turn directly towards the food plant. The small caterpillars first feed on the fine hairs with which the leaves of the silk plants are coated. The caterpillars then crawl around, the hairs causing the caterpillars a problem, only to then return to the vicinity of the egg and eat small holes in the leaf. These small holes are characteristic tracks of the young monarch butterfly caterpillars. After the first moult, the caterpillars turn to the leaf edges.

If the caterpillar is disturbed on its food plant, it drops to the ground, curls up and remains motionless for several minutes. If the disturbance occurs several times in quick succession, the time of immobility is shortened to around 50 seconds until, after around 15 disturbances, it no longer pretends to be dead and immediately crawls away. If the caterpillars drop off the plant, they then have to find this or another. The caterpillars are unable to smell their food plants or to distinguish them visually from other plants. That's why they crawl around in irregular paths on the ground looking for a suitable plant. With sensory cells on the maxillary palps , the caterpillars can feel whether it is a suitable plant. If there are only a few suitable plants, she may find none and starve.

The warning color of the caterpillars allows them to sit on top of the food plants and sunbathe undisturbed.

Some late-stage monarch butterfly caterpillars gnaw a small notch on the petioles and crawl to the tip of the leaf to snap off the leaf. Then they crawl onto the underside of the leaf and continue to eat. The supply of cardiac glycosides and milk juice into the leaf is thereby interrupted. This reduces the risk of the caterpillar being poisoned or the mandibles sticking together from the milky sap.

Breeding many caterpillars in a confined space can lead to cannibalism. The attacking caterpillar begins to eat the excrement of another caterpillar and then starts to eat it from behind. Such behavior is very unlikely in the wild, as the females almost always lay the eggs one by one on the leaves of the food plant and the caterpillars therefore do not live together in large numbers. The only exception are field observations in Spain, where pupae were eaten by caterpillars when many caterpillars were living on a plant.

butterfly

Migratory moths can be recognized by their flight behavior, in which obstacles are flown over. The migration of the moths is strongly influenced by the wind. When there is a tailwind, the moths often sail and fly several hundred meters high in order to take advantage of the wind that is favorable for them, while with a headwind they fly low above the ground, where the wind is weakest. During the migratory flights, the moths repeatedly make so-called “social flights”, in which the moths follow each other in a large circle at a height of about 30 meters, the flight consisting of fluttering and gliding. Often they are carried by the wind, the flight pattern resembles circling seabirds on the coast.

Non-migratory moths that fly around, visit flowers or look for suitable plants for oviposition have a rather aimless flight and fly around obstacles. Male moths fly higher in the area and also visit flowers on trees while the females usually fly close to the ground vegetation and look for suitable plants for laying eggs. In this aimless flight, your wings run through about 30 degrees of arc when the wing flaps and the wing flaps are interrupted by short gliding phases. The moths reach a speed of about 17 km / h. When the moths feel threatened and flee, they flap their wings violently, which then traverse 120 ° and flap vertically above their body. The moths reach a speed of over 30 km / h. The moths sometimes fly very high on hiking flights, they were observed with binoculars up to 500 meters above the ground, and hang-gliding pilots found them up to 1250 meters above the ground.

The life expectancy of the moths is around one month. However, when the moths migrate and go into diapause, they live for eight to ten months, with the moths only living for a month once they become fertile.

The spectrum of flowering plants visited by the butterflies is diverse. There were observed visits to flowers of the following plant families: Umbelliferae (Apiaceae), asclepiadoideae (Asclepiadaceae), cabbage family (Brassicaceae), honeysuckle (Caprifoliaceae), Crassulaceae (Crassulaceae), teasel family (teasel), heather plants (Ericaceae), spurge family (Euphorbiaceae) Legumes (Fabaceae), hydrangea family (Hydrangeaceae) Mallow family (Malvaceae), myrtle family (Myrtaceae), miracle flower family (Nyctaginaceae), evening primrose family (Onagraceae), orchids (Orchidaceae); Rose family (Rosaceae), buttercup family (Ranunculaceae), willow family (Salicaceae), nightshade family (Solanaceae), verbena family (Verbenaceae) and grass trees (Xanthorrhoeaceae).

The moths ingest pyrrolizidine alkaloids from dried plants of various species of the predatory family (Boraginaceae), daisy family (Asteraceae) and legumes (Fabaceae) , which make them more poisonous. In contrast to other types of Danaini, the males do not need them for the production of pheromones .

Reproduction

The males show territorial behavior and patrol their area in search of females. If a male becomes aware of a female, it will pursue it with rapid flight. If the female is not ready to mate, she will flee in a quick zigzag flight, avoiding the male. Females ready to mate begin a helical upward flight with the male chasing them. In between they break out and quickly fly away. This spectacle is repeated several times and the male overtakes the female and pulls out his tufts of hair on the abdomen. Later both of them sit on a leaf or a branch. The male fans with gentle flaps of his wings towards the female sitting behind him, who keeps his wings closed. After that, the male pulls in his tufts of hair and bends his abdomen towards the female's abdomen and the two unite. The male then flies short distances with the female attached to him, who continues to keep her wings closed. In addition to sperm, nutrients and cardiac glycosides are also transferred. The female uses the nutrients during egg production, which are particularly important after the winter, when the fat reserves are almost exhausted. The cardiac glycosides increase the toxicity.

In contrast to other Danaini, the tufts of hair are not required for successful mating in the monarch butterfly. The moths sometimes dip the abdomen with the tufts into the wing pouches, but do not transmit any fragrances because, unlike other species of the genus, they do not produce pheromones . This behavior seems to be a relic from the time when pheromones still played an important role in mating in the species. Instead of wooing the female with scents in flight, the monarch butterfly often has a brutal method of forcing mating. In flight, the male pounces on the female from above and holds onto him with his legs on the head, thorax and abdomen and forces them to land in a gliding flight. This behavior is only known from the monarch butterfly and the African monarch. Specially shaped tarsi help the males to hold onto the females. The widespread choice of partner by female butterflies does not exist with the monarch butterfly. This behavior led Miriam Rothschild to the following, often quoted, statement in 1978:

"The monarch butterfly could well be designated nature's prime example of the male chauvinistc pig."

“ The monarch butterfly can be described as nature's best example of the male chauvinist pig. "

In the wintering colonies, the females prefer to mate with males that are smaller and more flown away and cannot survive the return flight. Larger males in good condition make the return flight and only mate later near the oviposition sites. The females are mated up to 11 times and lay around 300 to 400 eggs individually on the underside of the leaves of the food plant over a period of two to five weeks. In bred butterflies with an ideal food supply, around twice as many eggs are produced; peak values ​​can even be over 1000 eggs.

The males lose weight in the form of water soon after mating and become brittle, bleached, and die. After mating, the first eggs develop slowly, so the migratory females lay most eggs towards the end of their migration. After that, they suffer the same fate as the males.

orientation

The monarch butterflies orient themselves on the sun during their migration and correct the azimuth during the day in order to maintain the course. By perceiving polarized ultraviolet radiation , this navigation is possible even when the sky is overcast. In addition, they have magnetite stored in their heads and can thus orientate themselves with the help of the earth's magnetic field and their magnetic sense . During their hikes, they also use landmarks such as the Sierra Madre Oriental , which they follow in autumn to the south with a slight eastward orientation, after previously flying a south-westerly direction through North America. Waters such as large rivers or lakes and the sea coasts also serve as orientation.

development

The egg caterpillar hatches around four to five days after laying eggs. The development time decreases with increasing temperature. At 17 ° C it takes a good 5 days, while the development time is shortened from 25.5 ° C to under 4½ days. Under favorable conditions, the caterpillars reach the prepupal stage after about 16 days. During this time they molt four times; The egg caterpillar, which weighs 0.54 milligrams, becomes a caterpillar that weighs around 1.5 grams and is six centimeters long. The weight gain over time is similar to a quadratic function . The speed of development depends heavily on the temperature, in damp and cool weather the development can take a long time, while higher temperatures and sunshine accelerate the development. Before each molt, the caterpillar becomes sluggish, it wanders around looking for a quiet place where it will molt within a few hours. Her body seems cramped, every now and then she jerks back and forth or hits left and right. The old skin rips open behind the head. With contractions it is pushed backwards. The caterpillar rests for a while until the new soft skin, especially the head capsule and the mouthparts, has hardened.

The caterpillars feed mainly on various silk plants , in North America 27 species have been recorded as food plants. Species of other genera from the subfamily of the silk plant family are rarely accepted. The eggs for the first generation are mainly laid on Asclepias oenotheroides , Asclepias viridis and Asclepias asperula , while the eggs for the second generation are mainly laid on common milkweed ( Asclepias syriaca ) and marsh milkweed ( Asclepias incarnata ). The moths very rarely lay eggs on the invasive neophyte Vincetoxicum rossicum , on which the caterpillars cannot develop.

In newly populated areas, the caterpillars have sometimes switched to other plant families. In the Canaries and Madeira, they feed on the spurge Euphorbia mauretanica and in Andalusia where the dog poison plants counted Cynanchum Acutum .

The mature caterpillar leaves the food plant and looks for a sheltered, shady place for the pupation many meters away. When she finds one, she spins a small pad of threads produced by glands on her head. Then she spins a strand in the middle of the mat that can be up to four millimeters long. Both take about three hours. It is attached to the strand with curved thorns that are arranged in a ring around the anal abdominal bones . The hanging caterpillar is shaped like a "J", the head is raised to the thorax. After a few minutes, the caterpillar skin breaks open behind the head and the skin of the dump doll appears. The doll is initially soft and flexible, it hardens over time. After 9 to 12 days of pupal rest, the butterfly hatches within three minutes. He pumps hemolymph into the wings to unfold them and waits for them to harden.

Monarch butterfly caterpillars in Barbados

In Barbados there is a remarkable interaction with silk beetles. The monarch caterpillars feed mainly on oscher ( Calotropis procera ) on the island , as the Indian milkweed ( Asclepias curassavica ) can only rarely gain a foothold due to the topology of the island. However, once it settles with bedbugs of the genus Oncopeltus , the caterpillars devour the plants so quickly that the bugs starve to death.

The populations and their migrations

Monarch butterflies on the move

The most extensive migrations are undertaken by the moths of the eastern population in North America, followed by the western population. The two populations are not entirely geographically isolated by the separating Rocky Mountains . In valleys in Idaho and Montana , especially on the tributaries of the Snake River , the moths of both populations migrate and gene flow occurs. In Australia and New Zealand, the moths only migrate over short distances.

Eastern population

The eastern population in North America lives between the eastern Rocky Mountains and the Atlantic coast. The majority of the population overwinters in a diapause in the volcanic mountains of Mexico's Sierra Nevada at an altitude of around 3000 meters. Only a very small part overwinters in the mild south of Florida and partly also reproduces in winter. In spring, the moths migrate north and east from their wintering places over several generations. On the way they lay eggs again and again, from which future generations develop.

First generation

After wintering in Mexico, last year's moths migrate north to Texas , Oklahoma , Arkansas , Louisiana , Mississippi , Alabama , Georgia , South Carolina , North Carolina and the south of Missouri and Kansas by the end of April . It seems that the moths want to return to the place where they lived as a caterpillar. Very few migrate further north to the Great Lakes, as few animals survive the migration in both directions over the great distance. The females lay only a few eggs in Mexico, with most laying them towards the end of their migration in the southern United States. The resulting first generation hatches in late April to early June. The migratory moths reach North Dakota , Minnesota and the Great Lakes area in late May and lay eggs in these areas as well. The moths of this generation can be found from southern Texas and the Gulf Coast to north of the Great Lakes. Since only a few overwinterers move north from south Florida and lay eggs in central and north Florida, only very few moths of the first and last generation fly north east of the Appalachians . The development is slow due to the often low temperatures and it takes 40 to 50 days for the eggs to develop into butterflies.

Second generation

The second generation moths hatch in June and July and only migrate a little further north and reach the northern limit of distribution in southern Canada at around 50 degrees latitude. They migrate more north-east and colonize the area between the Saint Lawrence River and the Atlantic and fly to New Brunswick , Nova Scotia and the east of Newfoundland . The food crops in the southern United States dry up in summer. Therefore, the local butterflies migrate north and south of the 33rd parallel there are almost no more butterflies to be found.

More generations

Due to the different rapid development in the various regions, a third and fourth generation flies together at the end of August / beginning of September and forms the late summer population with a large number of individuals, which moves south a little later. While the previous generations became fertile a few days after hatching, many of these animals remain sterile until after diapause . Some females that are fertile will lay more eggs on their way south and a fifth generation may arise in places. The dormancy is triggered by the short days, the lower temperatures and the dying food plants.

migration

Migration of the eastern and western population in the year

Hibernating moths in Mexico

The animals migrate from their 100 million hectare habitat to Mexico's Sierra Nevada from September to November and congregate on less than 20 hectares. On their hike, they find themselves at the same resting places every year and sometimes form large colonies over the night. The moths sit closer together in low temperatures and strong winds and form even larger colonies. At temperatures below 10 ° C, the moths cannot fly and, depending on the weather, also rest during the day. In sunshine and over 13 ° C, you can continue your hike. The moths need eight to ten weeks to migrate from Canada to Mexico, and four to six weeks from the southern regions. On average, they cover around 50 kilometers a day. Many moths die in the waters and on the roads during the migration. In some places the banks of the great lakes are littered with alluvial dead butterflies. The moths migrate in a south-westerly direction, starting east of Lake Huron , then they usually do not reach Mexico directly, but rather encounter the Gulf of Mexico and migrate in large schools along the coast. The moths from the east coast initially migrate south and encounter the Atlantic coast, which they migrate along before changing their flight direction west to the Gulf coast.

Around October they cross Texas to follow the Sierra Madre Oriental to the south in Mexico , after which they turn west and reach the volcanic mountains of the Sierra Nevada.

The origin of the moths is reflected in the winter quarters. The moths of the Great Plains fly to the westernmost places, those of the Great Lakes, which do not reach the Gulf Coast, about the middle ones. Butterflies reaching the Gulf Coast occupy the eastern places.

A small part of the eastern moths fly to Florida, most of them spend the winter there, often without diapause, and the rest fly to the Yucatán via Cuba . Others move to the Yucatán via northern Florida, Jamaica and Cuba. Large sleeping colonies of migratory moths are known from the Yucatán. It is not clear whether this is only the nominate form Danaus plexippus plexippus or also the subspecies Danaus plexippus megalippe , which is widespread in the Caribbean . A very small proportion of the moths that come across the Atlantic coast sometimes fly to Bermuda .

Winter in Mexico

Monarch butterflies suckle on the ground; Morelia, Mexico

The wintering quarters are in the south of Mexico in the states of México and Michoacán in the Sierra Nevada, a high plateau of volcanic origin. The approximately 30 winter colonies are spread over nine separate volcanic massifs, which are between 70 and 170 kilometers from Mexico City . In the mountains the Madrean Pine-Oak Woodlands predominate, mainly oaks grow up to 2900 meters, pines between 1500 and 3000 meters and firs ( Abies religiosa ) between 2400 and 3600 meters above sea level. Less widespread are cypress forests ( Cupressus lindleyi ), which grow between 2400 and 2600 meters, juniper heaths and grassy areas with finger herbs ( Potentilla candicans ). In places there are agricultural areas and bushland.

When the moths have arrived in the mountains, they fly around, observe the wind direction and look for sheltered places on trees, preferably on Abies religiosa . When the butterflies that arrive first have settled down, the following moths join, regardless of the wind direction, and dense clusters of butterflies form that can cover entire trees. When the wind changes, the moths that were previously on the leeward side are exposed to the cold wind. Since they cannot fly in the low temperatures in winter, they fall to the ground when the trees bend in the storm with rain or snowfall, which often occur in late December to early January. Whole clusters of butterflies are shaken from the tree tops and die on the ground. In mid-January and in February, the large grapes on the peaks dissolve and the moths migrate down the valley and form smaller and loose grapes. The moths then leave the trees again and again to suckle at the edge of small puddles and mud. Towards the end of February, when it gets warmer again, they leave the mountains and migrate north. Only a very small part remains in Mexico.

Western population

Wintering monarch butterflies in Santa Cruz

The western population in North America lives in the valleys of the western Rocky Mountains and the Cascade Range during the summer . It makes up about five percent of the total population and winters on the California coast on eucalyptus trees , Monterey pines ( Pinus radiata ) and Monterey cypresses ( Cupressus macrocarpa ). They overwintered on Platanus racemosa before they were heavily cut down by the white settlers.

On the pines, the moths form particularly dense grapes, whereas they sit more loosely together on the eucalyptus trees imported from Australia in the 1850s. The eucalyptus trees have spread widely and bloom in winter, so they are particularly valuable to the butterflies in this nectar-poor season. The animals at the northern wintering sites are inactive and stay in the same place over the winter. The southern moths are often active and suck nectar in between. Sometimes they change the wintering place. From mid-February the animals become more active and move to the northeast a few weeks later.

The more than 300 wintering places are almost exclusively in a 1000 kilometer long coastal strip from Marin County to Ensenada , on average about 2.5 kilometers from the coast. Only six places inland are known, of which a wintering place north of the Mojave Desert in the dry Saline Valley , 320 kilometers from the California coast, is a blatant exception. The concentrations of the moths rarely exceed 1000 animals, only eleven places are known where the concentrations had more than 50,000 individuals over several years. About 70 percent of the total western population winter between Santa Cruz County and Santa Barbara County .

A particularly large number of moths overwinter near Ventura , Carlsbad , Santa Cruz ( Natural Bridges State Park ), North Beach Campground in Pismo Beach ( San Luis Obispo County ) and the small town of Pacific Grove in Monterey County .

There is evidence that some moths are migrating from the Great Basin southeast via Arizona to Sonora . It is not yet clear whether this is a real migration or just a reduction in the distribution area over the winter.

Australia

Since the 1870s, the monarch butterfly has colonized large parts of eastern Australia and a small part of the west. The seasonal spread is related to the presence of silk plants, which are sensitive to drought and frost. In Queensland, most of the population breeds year round. In autumn, the moths retreat from New South Wales and southern Queensland and migrate north. Regular long-distance migrations are not observed, although the longest recorded migration of a butterfly is nearly 400 kilometers. The moths are concentrated in three areas, a coastal strip in northern New South Wales and southern Queensland, in the Sydney Basin and Hunter Valley, and around Adelaide . South of the 34th southern parallel, the animals are usually not fertile from autumn onwards, whereas part of the population in the Sydney region is always fertile. The ratio of fertile to sterile animals depends on the temperature.

New Zealand

In New Zealand, the migratory and wintering behavior of the monarch butterfly has been researched since around 1980, reports about wintering butterflies go back to the 1950s. The moths only cover short distances in New Zealand to hibernate together, very rarely more than 20 kilometers. The number of overwinterers fluctuates as much as the population in New Zealand as a whole due to the weather.

Some 100 hibernators were observed for the first time in 1959 on the North Island in Northland , Hawke's Bay and Nelson , in the following years their number sometimes fell to a few dozen and in 1962 again reached over 100 animals. Colonies with several thousand animals were observed in the North Island on Stephenson's Island , in the Bay of Tauranga and in the north of Auckland in May and June 1964.

The moths are frequently sighted in the Canterbury and Otago regions and occasionally in the Southland region . In Christchurch , on the east coast of the South Island , the moths gather in parks and gardens and have thus become a tourist attraction. In 2003, for example, a large number of overwinterers gathered. After a snowfall in 1992, the population on the South Island fell sharply.

Population dynamics

Size of the wintering areas in Mexico from winter 1993/94 to 2013/14 in hectares

About 90 percent of the eggs laid do not produce moths. Environmental conditions and especially natural enemies such as ants and parasitoids reduce the population at every stage. Up to ten percent of caterpillars do not reach the butterfly stage due to molting problems, bacterial, viral or fungicidal infection, poisoning by the cardiac glycosides and sticky mouthparts from the milk sap of the food plant. Temperatures above 35 ° C are fatal for the caterpillars, as are longer periods of frost for all stages. Low humidity and prolonged periods of drought, during which the food plants dry out, also have a negative effect.

The moths are very sensitive to frost, a few degrees below zero let many animals die. If the animals are moistened before the frost, for example through fog or rain, their frost hardiness is greatly reduced. Experiments showed that under dry conditions half of the animals survived −8.1 ° C, at −15 ° C all died. Half of the humidified animals died at −4.4 ° C and all died at −7.8 ° C. Moisture also accelerates freezing; at −4 ° C it only takes three hours for moistened butterflies, while dry butterflies are not frozen to death even after 24 hours.

The strength of the western population is subject to much greater fluctuations than the eastern population, as the food plants are less widespread and due to the dry climate in many places, they do not thrive every year. The population size correlates strongly with the degree of drought in a year. In 1997 about 1.2 million animals were counted and after several dry years it was not even 100,000 in 2002. Many wintering sites remained orphaned in 2002, although they offered the same conditions as in previous years. There was no deforestation or construction.

The several 100 million moths of the eastern population, which develop in summer depending on the year, suffer initial heavy losses during their long migratory flights, for example due to weather influences and road traffic. Others come through the long diapause caused by the cold weather and predators . The weather in the Sierra Nevada has hit the animals harder for several decades through illegal logging. Felling just a few trees can lead to more butterflies dying, as they get wet more easily and are more exposed to cold winds at night, so that the frost-sensitive animals die. On the other hand, they are exposed to stronger sunlight during the day, which leads to higher energy consumption and thus they use up their fat reserves. Cold snaps repeatedly kill millions of animals, such as in 1981 when around 2.7 million moths died. The longest observed storm in 1981 lasted January 12-23 and killed about 42 percent of the population. In January 1992, prolonged cold and humid weather killed 90 percent of the butterflies in the Sierra Herrada colony, located at 3,164 meters. A devastating cold snap and storm from January 12 to 16, 2002, in which the moths were previously wet from rain, killed 75 percent of the population with around 500 million animals. About 5000 dead butterflies per square meter were counted at the wintering sites. Two years later, on January 18 and January 31, two storms killed about 70 percent of the moths. The following summer was the coolest since 1992 and the summer population had little growth. In the following winter of 2004/2005, the lowest number of overwintering monarch butterflies was registered in Mexico. The colonies took up only 2.2 hectares, the lowest figure in at least 12 years, and probably even since observations began in the late 1970s. The colonies had the greatest extent in 1996/1997 with almost 22 ha. In the following years there was a slight recovery, but the populations decreased again in the following years and reached a new low of only 0.67 ha in the winter of 2013/14 . In addition to extreme weather conditions, the main causes of the decline in recent years are the sharp decline in suitable food crops in the USA and Canada due to the cultivation of pesticide-resistant plants on a large scale and the displacement of food crops by introduced plants.

Infections

The bacterium Micrococcus flaccidifex danai kills the caterpillars before they pupate . Micrococcus flaccidifex is patented as a biological pest control.

Parasites

The protozoon Ophryocystis elektroscirrha parasitizes the moths in their entire range. The parasite weakens the moths, the infected animals fly more slowly and cannot cover such long flights. As a result, the spread of the parasite is strongly inhibited in particularly far-migratory populations, as only non-infected or slightly infected animals can cover the long distances to the winter quarters. The degree of parasitization of the eastern population is lower in the west (east of the Rocky Mountains to the Appalachians) than in butterflies in the east of the range, near the Atlantic coast. The moths that migrate to Florida or the native moths in Florida have a lower selection pressure, whereas the long migration to Mexico favors resistant animals. Differences in wing size and shape, on the other hand, have no significant influence on the speed and overall distances. The spores of Ophryocystis elektroscirrhas are eaten by the caterpillars so that the species can reproduce asexually and later sexually in its body. In the last days of the pupal stage, new spores are formed which are found on the scales of the wings when they hatch. The spores are deposited on the food plants or are brought onto the surface of the eggs by the moths when they lay eggs. The egg caterpillars eat the spores on the egg shell or the caterpillars ingest the spores through the food plant and the cycle begins again. When mating, the spores can be transferred from the male to the female, which in turn can infect the eggs. The transmission from butterfly to butterfly is also possible when the animals are close together, which often occurs when overwintering in the large colonies. How this affects the infection rate of the offspring has not yet been researched. If the infection is very severe, the pupa will develop gray spots and it will be so difficult for the moths to hatch that they can sometimes not leave the pupae completely.

Parasitoids

Over 20 different parasitoids of the monarch butterfly are known. In North America, an average of 13 percent of caterpillars are parasitized, almost exclusively by flies of the species Lespesia archippivora . The rate fluctuates strongly from year to year and from region to region, so that in individual cases up to 90 percent are parasitized. The caterpillars are parasitized in all stages, with caterpillars being preferred in the late second to fourth stage. In the advanced stages there is occasional superparasitation, which means that more than one female fly lays its eggs in a caterpillar. In the final stage, the rate drops as these caterpillars are able to shake off the flies. Up to ten flies develop from the parasitized caterpillars, with around 35 percent only developing one, and around 15 percent each developing two to three flies.

Lespesia archippivora does not specialize in the monarch butterfly and parasitizes at least 25 species of butterflies from 14 families and one hymenoptera. The dose of cardenolides absorbed by the food plant has no influence on the degree of parasitization. Lespesia archippivora is parasitized by a species of wood wasps from the family of Perilampidae . Their females attach their eggs to leaves. After the larvae hatch, they invade the body of the main host and look for the larva of the main parasite. They only develop further when it pupates.

Other known parasitoids of the monarch's fold are:

• Fly (Diptera): Brachymeria obscurata , Buquetia obscura , Chaetogaedia monticola , Compsilura concinnata , Epicampocera obscura , Eusisyropa virilis , Exorisla Mella , Lespesia archippivora , Lespesia schizurae , Madremyia saundersii , pecosensis Phryxe , Phryxe vulgaris , Paradrino laevicula , Sturmia convergens , Winthemia diversa
• Hymenoptera (Hymenoptera): Trichogramma minutum , Trichogramma Intertmedium , Echthromorpha fuscator

insects

Red fire ant workers particularly hunt for the caterpillars and eggs of the monarch butterfly.

Large Chinese mantis with a captured monarch butterfly

The predators of eggs and caterpillars include beetles, such as ladybirds , which eat the eggs, the predatory bug species Cermatulus nasalis , which suckle the caterpillars, and lacewings (Chrysopidae) which eat the young caterpillars.

Ants drag the eggs into their burrows and kill the caterpillars. The red fire ant ( Solenopsis invicta ) introduced into the southern United States poses a major threat to eggs and caterpillars and contributes to a relatively low population density and patchy distribution in the southern states. However, the fire ant is also displacing native species of ants, which also lead to large losses in the eggs and caterpillars, so that the losses of the moths are probably balanced.

In New Zealand, ants of the species Technornyrmex albipes prevent monarch butterfly caterpillars from settling on food plants. Also in New Zealand, Cermatulus nasalis and Oechalia schellenbergii from the family of stink bugs (Pentatomidae), Polistes chinensis and Polistes humilis humilis from the family wasps (Vespidae) in the subfamily of field wasps (Polistinae) and the fishing insect Miomantis caffra have been identified as predators. Another important enemy of the monarch butterfly is the great Chinese mantis ( Tenodera sinensis ), which was originally native to East Asia and was introduced in the northeastern parts of the United States and also counts as a terrifying species , which is not deterred by the glycosides of the adult moths and the Avoids toxins absorbed by the caterpillars by biting open the stomach region of the caterpillar and letting the digestive organs fall out of the caterpillar during the feeding process.

Vertebrates

The diademed jay eats monarch butterflies in Mexico

The red-eared bulbul prefers the orange nominate form of the monarch butterfly in Hawaii

Because of the cardiac glycosides, which make the majority of monarch butterflies inedible for vertebrates, the hunting pressure from lizards, frogs, mice and birds is relatively low. However, some birds have adapted and can eat poisonous caterpillars and moths. The Cayenne tyrant ( Myiarchus tyrannulus ), which belongs to the family of tyrants , eats wintering moths in Mexico. It tears off the wings before eating the moths. Icterus galbula abeillei from the genus of the Trupiale and the Schwarzkopf Kernknacker ( Pheucticus melanocephalus ) from the genus of the Kernknacker (family of the cardinals ) eat a significant amount of butterflies per day, so that, with an average wintering duration of 135 days, they eat about nine percent of Population fall victim. In addition, even the eating Steller ( Cyanocitta stelleri ) and the Scott-Trupial ( Icterus parisorum ) fewer moths. It is unclear whether the birds prefer to eat males because of their low toxicity or higher fat content.

In New Zealand, for example, the bronze cuckoo ( Chrysococcyx lucidus lucidus ), which eats butterflies, and the gloss-spot drongo ( Dicrurus hottentottus ), which eats caterpillars, have been identified as enemies.

On the Hawaiian island of Oʻahu, the red- eared bulbul ( Pycnonotus jacosus ) and Rußbülbül ( Pycnonotus cafer ) feed on the only weakly poisonous, normally colored butterflies, which favors the white form nivosus and explains their strong occurrence there.

In addition to birds, mice are other important hunters of moths in Mexico's wintering quarters, killing around five percent of them. The deer vole ( Peromyscus maniculatus ), Peromyscus spicilegus and the Mexican vole ( Microtus mexicanus ) absorb the toxins only weakly through their stomach and intestines and can therefore eat thousands of monarch butterflies every night.

Protection from enemies

The caterpillars can ingest cardiac glycosides such as calactin , calotropin and eriocarpa through their food plants , which make them and the later pupae and moths inedible for vertebrates. Birds that eat moths enriched with cardiac glycosides vomit. This behavior was in Star ( Sturnus vulgaris ) and Blue Jays ( Cyanocitta cristata bromia observed), who was seriously ill for about half an hour. A particularly large number of cardiac glycosides are absorbed via Asclepias curassavica (calactin and calotropin) and A. humistrata . On the other hand, Gonolobus rostratus does not contain any glycosides and the moths are edible for the birds, just like moths whose caterpillars ate on A. syriaca , A. tuberosa and A. incarnata , although these plants contain glycosides. The caterpillars accumulate some of the glycosides, such as calactin, calotropin and eriocarpa, in their bodies and the concentration is significantly higher than that of the plants. On the other hand, the important glycosides labriformadin and labriformin are not enriched by A. eriocarpa and uscharidin by A. curassavica , the latter being converted into calactin and calotropin.

Overall, female moths accumulate more glycosides than males and the concentration increases from south to north within the eastern summer population. The moths of the western population have a higher proportion of edible moths than those of the eastern population, but they reach higher peak values ​​of glycosides.

research

In 1857, the British naturalist William Stewart Mitchell d'Urban , who temporarily lived in Canada, described migratory monarch butterflies in the Mississippi Valley for the first time: "Such vast numbers as to darken the air by the clouds of them" (in such large numbers that the air seemed to darken through their clouds). Ten years later, large groups of monarch butterflies resting on trees were described for the first time. The spectacle on the prairie of southwestern Iowa was described by Allen in the following words: “in such vast numbers, on the lee sides of trees, and particularly on the lower branches, as almost to hide the foliage, and give to the trees their own peculiar color ” (in such enormous quantities on the leeward side of the trees, especially on the lower branches, as if they wanted to hide the foliage and give the trees their own striking color). Even then, this behavior was interpreted as protection from the prairie wind and also as part of a south hike in autumn.

The American entomologists Benjamin Dann Walsh and Charles Valentine Riley published the first evidence of the massive migrations of monarch butterflies in 1868. Three years later, Riley described the biology and way of life of the monarch butterfly and its mimicry with Limenitis archippus and thus founded research on the monarch butterfly.

In 1881 the wintering sites of the western population were discovered in California, those of the eastern population remained undiscovered for almost 100 years. It was initially suspected that they wintered on the Gulf Coast, but doubts soon arose. Today it is clear that they cannot survive there due to their sensitivity to frost with the hard frosts that occur again and again. The amateur entomologist and secretary of the Entomological Society of Ontario John Alston Moffat had correctly deduced this as early as the turn of the century.

Edward Bagnall Poulton , 1903–1904 President of the Royal Entomological Society of London , suspected in 1909 that the caterpillars of the monarch butterfly feed on poisonous silk plants to protect themselves from hunters. This was only confirmed by Parsons in 1965 when he found out that the cardenolides make the caterpillars and moths poisonous and bitter-tasting.

A freshly tagged monarch butterfly during Cape May Bird Observatory's Program , New Jersey , on October 11, 2008

The book The Migration of Butterflies (1930) by the British entomologist Carrington Bonsor Williams encouraged the Canadian Frederick Urquhart and in 1937 he marked the first butterflies to learn more about their migrations. At that time it was assumed that the moths also overwinter east of the Rocky Mountains in California, which he doubted because their number in California seemed too small to him. At first there was no success. He continued researching various marking methods until he finally found a simple and weatherproof method through a friend's tip. The stickers, about 6 by 12 millimeters in size, called alar tag , from the Latin alar for wings, were a breakthrough for marking butterflies. They were labeled "Send to Zoology University of Toronto Canada" .

His wife, with whom he researched monarch butterflies for a lifetime, wrote an article about tagged monarch butterflies for a magazine in 1952. This post contained a call for volunteers to help them with their work. 12 people responded and founded the International Migration Association . The Urquharts provided the materials for the labeling and trained the volunteers; 20 years later the association already had over 600 members with thousands of helpers. These marked hundreds of thousands of moths and thus the Urquharts succeeded in gaining new knowledge about them. It turned out that the moths flew up to 130 kilometers in a day, but only in daylight, and that they avoided wind and open water. The direction of flight of the moths was from northeast to southwest and the Urquharts traveled to California and the Gulf of Mexico , but without finding the wintering quarters.

In 1972, Nora wrote to Mexican newspapers and called for cooperation in the search for the butterflies. The American engineer Ken Brugger from Mexico City then drove around Mexico in search of butterflies for the next few years. In 1974 he married Cathy and the two butterfly lovers kept looking. They found dead animals again and again and got closer and closer to the wintering quarters. In 1975 they showed woodcutters dead animals and they finally showed them the way to the quarters of the monarch butterflies on Cerro Pelón , 120 kilometers west of Mexico City. Then they called the Urquharts and told them that they had found millions of butterflies. The following year the Urquharts traveled to Mexico themselves and visited the site. The ground was covered with butterflies and the trees were full of them. A branch broke off under their weight, including a moth marked in Minnesota . That same year, Frederick Urquhart published an article in National Geographic describing the phenomenal concentration of wintering monarch butterflies.

Urquhart doubted that the moths could survive the flight across the Atlantic from America to Europe, since they only fly during the day, cannot rest on the water as he demonstrated, and the route could not be covered in a day. He suspected that the moths, which appear again and again on Europe's coasts, came on ships as caterpillars or pupae and left the ship near the coasts. However, the view has prevailed that the moths can actually be drifted across the Atlantic during strong storms, since North American migratory birds have often been spotted along with the moths on the European coasts after strong storms.

Marking butterflies is very complex and only about one per thousand is reported later and has flown over 100 kilometers. In the early 1980s, the American zoologist Lincoln Pierson Brower therefore examined the amount and pattern of cardiac glycosides in the butterflies that they ingested as caterpillars. With this he was able to limit the breeding areas of the moths, since different silk plants have a “fingerprint” due to different glycosides in certain proportions and the distribution areas of the individual species are different.

Other researchers examined the butterflies' sense of direction using their own solar compass and their magnetic sense .

Numerous initiatives are recording data on migratory monarch butterflies to learn more about their way of life. Some of them mark moths, such as Monarch Watch ( University of Kansas ) and the Monarch Monitoring Project in New Jersey . Journey North observes migratory animals in North America, including the monarch butterfly.

Systematics

After the first description in 1758 as Papilio plexippus by Linnaeus using a butterfly from Kendall , New York, USA, the monarch butterfly has experienced many different taxonomic classifications and regroupings. This led to a number of generic names and species…. Seitz assigned him to the genus Danais in 1908 . Two years later it was called Danaida (Anosia) archippux ( Fabricius ) by Fruhstorfer , while the name plexippus was used for a long time for the species now known as Danaus genutia . At this time, the monarch butterfly can often be found in literature as archippus . In 1939 Forbes assigned the butterfly to the genus Danaus as D. (Danaus) erippus menippe ( Huebner ) and D. (Danaus) erippus megalippe ( Hübner ), while in the same year d'Almeida classified it as Diogas curassavicae ( Fabricius ). Talbot shortened two years later Talbot's the name on Danaus Menippe ( Huebner ). The name Danaus plexippus (L.) , which is still valid today, has been used since 1971 .

The specific epithet is derived from Plexippos the son of Phineus and Cleopatra and the generic name comes from Danaos (Latin Danaus), king of Argos in the Peloponnese , the father of the 50 Danaids. Both are part of Greek mythology .

In addition to the migratory nominate form Danaus plexippus plexippus , the following subspecies are described:

• D. p. nigrippus ( Haensch , 1909), distributed in northern South America through Central America to Nicaragua.
• D. p. tobagi Clark 1941, widespread in Northern Brazil, Guyana, Suriname, French Guiana and Trinidad and Tobago.

There are three subspecies in the Antilles:

• D. p. megalippe ( Hübner , 1826) dark subspecies, Antilles, hybrids with D. p. plexippus is found in Espaniola, Puerto Rico. The caterpillars are also very dark, as the dark band is much wider than that of D. p. plexippus and takes up almost the entire space of the yellow ribbon.
• D. p. portoricensis Clark 1941, the subspecies can be recognized by the reduced or missing white dots on the tip of the forewing.
• D. p. leucogyne ( Butler , 1884)

The status of the subspecies is not clear, some of them live in the same areas. No migration behavior or the formation of colonies is known from any of the subspecies.

Hazard and protection

The caterpillars are primarily tied to silk plants and especially to the genus silk plants as a food source. If these are combated, it has a negative impact on population size. In the USA and Canada, the silk plants are sometimes viewed as weeds and are controlled with herbicides, for example on the roadside and on agricultural land. For many years, Fred Urquhart and his wife campaigned for the preservation of the natural occurrence of silk plants in Canada and the USA, in some Canadian provinces and in the USA the silk plants have been and are still classified as harmful by the authorities. Even so, in many flower gardens the plants are planted for their appearance and scent.

In Mexico and the Caribbean there is some superstition that cows are poisoned by silk plants. In Trinidad and Tobago, the silk plants are therefore called a crazy herb . In fact, the cows ignore the plants in the pastures and are not harmed. Nevertheless, they are fought in places.

The World Conservation Union (IUCN) has included the monarch butterfly in its invertebrate red book. However, not as an endangered species, but as an endangered natural phenomenon - a category specially created for this purpose. Even though many millions of monarch butterflies still live in eastern North America, the protective measures serve the goal of preventing further loss of a migratory species in North America, after the pigeon ( Ectopistes migratorius ) and the rock crest ( Melanoplus spretus ) became extinct for over 100 years.

Canada

In Canada, the monarch butterfly is protected by the Federal Species at Risk Act (SARA) and The Committee on the Status of Endangered Wildlife in Canada (COSEWIC), each in the Special Concern category . Long Point and Prince Edward Point in Prince Edward County (Ontario) and Point Pelee National Park in Essex County , Ontario are designated as monarch butterfly sanctuaries, the latter has also been protected by the Canada National Parks Act since 1995 .

United States

Some California wintering sites are at risk from land use, while others in the state, counties, and public parks are protected. In Pacific Grove about since 1938. The parasite Ophryocystis elektroscirrhas was only introduced into the western population from the east during experiments with butterflies and represents a relatively new threat.

Contrary to initial fears , the danger posed by transgenic maize is very low. From 1000 pollen / cm² a toxic effect sets in on the caterpillars. The pollen concentration on the silk plants is only between 50 and 170 pollen / cm² even during the main flowering period of the grain in the immediate vicinity of the fields.

A major danger is the conversion of agriculture from grain to soy, which worsens the conditions for the silk plants. The use of herbicides destroys the young silk plants in the main breeding areas on the edge of the fields in spring. In addition, sources of nectar for the moths are destroyed.

The organizations that collect data on monarch butterflies are also committed to protecting it. The Xerces Society , which does not collect data on migrations, is particularly committed to protecting the western population.

In 2016 the WWF announced that the American monarch butterfly population had "noticeably recovered". Almost four times as many butterflies arrived in winter quarters in central Mexico than in the previous year. However, the trend for the monarch butterfly is still pointing downwards globally.

Mexico

The moth is particularly endangered by the concentration of the eastern North American population on a few hectares in Mexico during the winter months. These wintering areas are threatened by illegal logging. In 1980, all wintering sites in Mexico were protected by presidential decree, but without defining the areas. In 1986 a protected area of ​​over 16,000 hectares was designated. At the end of 2000, the Monarch Butterfly Biosphere Reserve (MBBR) was expanded to over 56,000 hectares, of which over 13,000 hectares are in the core area. The land in the reserve is owned by 59 ejidos , 13 indigenous communities and 21 private owners. The communities affected by the enlargement receive economic support from the Monarch Butterfly Conservation Fund (MBCF), which was founded in the same year. Compensation is paid for lost logging rights. The fund is financed by private donations from the United States, the Mexican federal government and the governments of the states of México and Michoacán . The World Wildlife Fund and the Mexican Fund for Nature Conservancy jointly manage the MBCF. The greatest threat to the MBBR is illegal logging. Between 2001 and 2003 alone, 370 hectares were felled in the buffer zone (Francisco Serrato y Emiliano Zapata ejido) and 140 hectares in the core area. The communities affected by illegal logging receive almost no support from the state. They try to dig trenches on their own initiative in order to prevent the removal of wood, whereby large trenches several meters wide and deep only with heavy equipment have a somewhat longer-term effect. Small trenches that are dug with a pick and shovel are soon filled in again.

The protected area includes the Cerro Altamirano (3320 meters above sea level), the Cerro Pelón (3500 m), the Sierra Chincua and the Sierra el Campanario (3640 m) and the Cerros Chivatí-Huacal (3180 m) in the Sierra Chivati in Michoacán. Outside the reserve are Palomas , Piedra Herrada and San Francisco Oxtotilpan in the state of México and San Andres , Pizcuaro , Puerto Morillo and Puerto Bermeo in Michoacán. In Chivatí-Huacal, monarch butterflies have not hibernated since the heavy deforestation at the end of the 1980s; on Cerro Pelón all slopes except for a few southern slopes were so heavily cleared within ten years that only a few moths hibernate.

At the beginning of 2020, two environmentalists who had campaigned for the monarch's protected areas were murdered within a few days.

Another danger for the moths arises from the increasing traffic. Investigations on the Mexican highways Mex-057 and Mex-40D, over which the moth migration route leads, revealed a large number of dead specimens at the roadside. According to projections in autumn 2018, 196,500 adults fell victim to traffic there. Since the migratory moths pass several other roads and fly very low in bad weather, the death rate is likely to rise further.

Cultural history

The arrival of the monarch butterflies in Michoacán coincides with the Día de Muertos (Day of the Dead), which is traditionally a celebration of the deceased in Mexico. Even before the arrival of Europeans in America, the moths, which appeared in large numbers, symbolized the return of the souls of their ancestors for the natives .

The monarch butterfly was in the 17th century after Wilhelm III. (1650–1702), named King of England, Scotland and Ireland. He was a native prince of the Principality of Orange in France. The early settlers called the butterfly King Billy . It had many other names over the years, including Milkweed Butterfly , Storm King and The Wanderer , the latter of which is still in use in Australia today.

The monarch is state insect in Alabama , Idaho , Illinois , and Texas , and the state butterfly in Minnesota , Vermont, and West Virginia . In 1989 he was nominated for the National Insect of the United States of America and he is the National Insect of Canada.

Tourism developed in the wintering areas in California and much later in Mexico. California has motels with names like Butterfly Trees Lodge and Monarch Lodge . Souvenirs with butterflies, such as brooches and pins, as well as prepared butterflies are offered. In Pacific Grove there is a festival for the arrival of the butterflies in autumn with a parade with children in colorful costumes to symbolize butterflies. The Rosario wintering site in the Sierra Campanario, which has been developed for tourism, is suffering from illegal logging in its vicinity. The area was only sparsely visited in 2001/202 and completely deserted in 2003/2004 and 2004/2005.

In addition to numerous initiatives to observe and protect the moths, there is the University of Minnesota's Monarch Lab , for example, which appeals to students and teachers with its Monarchs in the Classroom initiative . It tries to impart knowledge about the ecology, the way of life and the development of the monarch butterflies and to get students excited about the topic.

In 2005, Francisco "Vico" Gutiérrez accompanied monarch butterflies for 72 days on their migration from Canada to Mexico with his ultralight aircraft Papalotzin (from Nahuatl (Aztec) Papalotl for butterfly and tzin for royal). Photographers and filmmakers accompanied him on his 4,375 mile flight. They filmed the entire trip funded by the World Wildlife Fund, Telcel and the state of Michoacán and planned to turn it into a one-hour documentary. On the journey they stopped and talked to well-known lepidopterists and biologists about the dangers for the monarch butterflies. The film was released in 2007 on DVD in English and Spanish under the title Papalotzin - The Journey of The Monarch Butterfly .

Many popular science books have been published about the monarch butterfly and it is also the subject of numerous children's books, such as the bilingual book (English and Spanish) Madalynn the Monarch Butterfly and Her Quest to Michoacan / Madalynn La Mariposa Monarca y Su Aventura Por Michoacan or Hurry and the Monarch , a children's book about a turtle who befriends a monarch butterfly in Texas and learns more about its life.

literature

Used literature

• Urquhart, Frederick Albert: The Monarch Butterfly: International Traveler . Nelson Hall Publishers, Chicago, USA 1987, ISBN 978-0-8304-1039-2 , pp. 232 .
• Karen S. Oberhauser, Michelle J. Solensky (Eds.): The Monarch Butterfly: Biology and Conservation . Cornell University Press, Ithaca and London 2004, ISBN 0-8014-4188-9 , pp. 248 .
• Richard Irwin Vane-Wright & PR Ackery (Eds.): Milkweed Butterflies. Their Cladistics and Biology . Cornell University Press, Ithaca and London 1984, ISBN 978-0-8014-1688-0 , pp. 425 .
• Williams, Carrington Bonsor: The migratory flights of insects: Introduction to the problem of the migratory behavior of insects with special consideration of butterflies . Paul Parey, Hamburg, Berlin 1961, pp. 232 .

further reading

• Anurag A. Agrawal: Monarchs and Milkweed. A Migrating Butterfly, a Poisonous Plant, and their Remarkable Story of Coevolution . Princeton University Press, Princeton, New Jersey, USA 2017, ISBN 978-0-691166353 .
• Stephen B. Malcolm, Myron P. Zalucki (Eds.): Biology and Conservation of the Monarch Butterfly . Natural History Museum of Los Angeles County, 1993, ISBN 978-99940-0-921-3 .
• A field guide to monarch caterpillars (Danaus plexippus) . In: Karen Oberhauser (Ed.): Evolution and Behavior . Department of Ecology, University of Minnesota, 1997.
• Williams, Carrington Bonsor: The Migration of Butterflies . Oliver & Boyd, Edinburgh, UK 1930, p. 473 .
• Williams, Carrington Bonsor: Insect Migration . In: The New Naturalist . tape 36 . Collins, London, UK 1958, pp. 237 .

Web links

Commons : Monarch Butterfly  - Album with pictures, videos and audio files

Wiktionary: Monarch butterfly  - explanations of meanings, word origins, synonyms, translations

• Monarch Lab - Biology and Migratory Behavior
• Butterflies and Moths of North America - Monarch
• Monarch Larva Monitoring Project (English)
• Monarch Watch (English)
• The Journey North (English)
• Report on the feeding of monarch butterflies by the Great Chinese Mantis from the National Geographic website ( Link )
• Spektrum .de: Captured monarch butterflies lose their compass June 25, 2019

Individual evidence

1. ↑ Badische Zeitung , February 11, 2014, Sandra Weiss: badische-zeitung.de: The population of Mexican monarch butterflies is shrinking (February 20, 2014)
2. ↑ Vane-Wright & Ackery (1984), p 77
3. ↑ ^{a b c} Michael Boppré: The American Monarch: Courtship and chemical communication of a peculiar Danaine butterfly . In: SB Malcom & MP Zalucki (eds.): Biology and Conservation of the Monarch Butterfly . Natural History Museum of Los Angeles County, Los Angeles 1993 ( fzi.uni-freiburg.de [PDF; 3.0 MB ; accessed on September 26, 2008]).
4. ^ Lawrence Gibbs and Orley R. Taylor: Reading Room - Articles: The White Monarch. monarchwatch.org, June 1998, accessed March 2, 2008 . 
5. ↑ Urquhart (1987), p. 64ff
6. ↑ Urquhart (1987), pp. 15ff
7. ↑ ^{a b c d} Felipe Gil-T .: A new hostplant for Danaus plexippus (LINNAEUS, 1758) in Europe. A study of cryptic preimaginal polymorphism within Danaus chrysippus (LINNAEUS, 1758) in southern Spain (Andalusia) . In: Atalanta . tape 37 , no. 1 , 2006, ISSN  0171-0079 , p. 143–149 ( researchgate.net [PDF; 317 kB ; accessed on September 21, 2008]).
8. ^ Smith, David AS; Lushai, Gugs & Allen, John A .: A classification of Danaus butterflies (Lepidoptera: Nymphalidae) based upon data from morphology and DNA . In: Zoological Journal of the Linnean Society . tape 144 , no. 2 , 2005, p. 191-212 , doi : 10.1111 / j.1096-3642.2005.00169.x .
9. ↑ Williams (1961), p. 26
10. ↑ Vane-Wright & Ackery (1984), p 46
11. ↑ David B. Ritland: Mimicry-Related Predation on Two Viceroy Butterfly (Limenitis archippus) Phenotypes . In: University of Notre Dame (Ed.): American Midland Naturalist . tape 140 , no. 1 . Notre Dame July 1998, p. 1-20 ( HTML [accessed February 10, 2008]).
12. ^ Tree of life
13. ↑ ^{a b c d e} Vane-Wright & Ackery (1984), p. 202
14. ↑ ^{a b} Stephen Pawson & Lisa Berndt: Observations of Monarch butterfly overwintering behavior in Christchurch . In: New Zealand Entomologist (Ed.): The Weta . tape 27 , no. 1 , 2004, p. 22 ( ento.org.nz [PDF; 200 kB ; accessed on March 2, 2008]).
15. ^ RI Vane-Wright & R. de Jong: The butterflies of Sulawesi: annotated checklist for a critical island fauna . In: Zool. Relative band 343 . Leiden 2003, ISBN 90-73239-87-7 , pp. 1–16 ( PDF (3.5 MB) [accessed February 28, 2008]).
16. ^ VC Neves, JC Fraga, H. Schäfer, V. Viera, A. Bívar de Sousa & PV Borges: The occurrence of the Monarch butterfly, Danaus plexippus L. in the Azores, with a brief review of its biology . In: University of the Azores (ed.): Arquipélago - Life and Marine Sciences . 18a, 2001, ISSN  0873-4704 , p. 17–24 ( horta.uac.pt [PDF; accessed February 28, 2008]).
17. ^ M. Wiemers: The butterflies of the Canary Islands. - A survey on their distribution, biology and ecology (Lepidoptera: Papilionoidea and Hesperioidea) . In: Linn. Belgian band 15 , 1995, p. 63-84, 87-118 ( researchgate.net [accessed October 14, 2012]).
18. ^ J. Fernández Haeger, D. Jordano & M. León Meléndez: Status and conservation of Asclepiadaceae and Danaus in southern Spain . In: J. Insect Conserv. tape 15 , 2011, p. 361-365 , doi : 10.1007 / s10841-010-9354-7 .
19. ↑ Urquhart (1987), p. 107ff
20. ↑ Urquhart (1987), pp. 140ff
21. ↑ Zalucki, Myron P. and Clarke, Anthony R .: Monarchs across the Pacific: the Columbus hypothesis revisited . In: The Linnean Society of London (Ed.): Biological Journal of the Linnean Society . tape 82 , no. 1 . Blackwell Publishing, 2004, pp. 111-121 , doi : 10.1111 / j.1095-8312.2004.00322.x .
22. ↑ Urquhart (1987), p. 70
23. ↑ Oberhauser & Solensky (2004), p 90
24. ↑ ^{a b c d} Lincoln P. Brower: Monarch Butterfly Orientation: Missing Pieces Of A Magnificent Puzzle . In: The Journal of Experimental Biology . tape 199 . The Company of Biologists Limited, 1996, p. 93–103 ( jeb.biologists.org [PDF; 280 kB ; accessed on September 19, 2008]).
25. ↑ Urquhart (1987), p. 74
26. ↑ Vane-Wright & Ackery (1984), pp 75ff
27. ↑ Vane-Wright & Ackery (1984) 78
28. ↑ Oberhauser & Solensky (2004), Chapter 1, pp. 3ff
29. ^ Steven M. Reppert and Jacobus C. de Roode: Demystifying Monarch Butterfly Migration. In: Current Biology. Volume 28, No. 17, pp. R1009 – R1022, 2018, doi: 10.1016 / j.cub.2018.02.067 .
30. ↑ I. Sauman, AD Briscoe, H. Zhu, D. Shi, O. Froy, J. Stalleicken, Q. Yuan, A. Casselman, SM Reppert: Connecting the navigational clock to sun compass input in monarch butterfly brain. In: Neuron. Volume 46, Number 3, May 2005, pp. 457-467, ISSN  0896-6273 . doi: 10.1016 / j.neuron.2005.03.014 . PMID 15882645 .
31. ↑ Jason A. Etheredge, Sandra M. Perez, Orley R. Taylor & Rudolf Jander: Monarch butterflies (Danaus plexippus L.) use a magnetic compass for navigation . In: Proceedings of the National Academy of Sciences (PNAS) . tape 96 , no. 24 , 1999, pp. 13845–13846 ( pnas.org [PDF; 60 kB ; accessed on September 27, 2008]).
32. ↑ Heather R. Mattila & Gard W. Otis: A comparison of the host preference of monarch butterflies (Danaus plexippus) for milkweed (Asclepias syriaca) over dog-strangler vine (Vincetoxicum rossicum) . In: Entomologia Experimentalis et Applicata . tape 107 . Blackwell Publishing, 2003, pp. 193–199 , doi : 10.1046 / j.1570-7458.2003.00049.x ( HTML [PDF; accessed September 21, 2008]).
33. ↑ Caterpillar Food Sources. Monarch Butterfly NZ Trust, accessed February 19, 2008 . 
34. ↑ Urquhart (1987), p. 41
35. ↑ Vane-Wright & Ackery (1984), p 98
36. ↑ Urquhart (1987), p. 161
37. ↑ Urquhart (1987), pp. 169f
38. ↑ Urquhart (1987), p. 92
39. ↑ ^{a b} Oberhauser & Solensky (2004), p. 79
40. ↑ Urquhart (1987), p. 138
41. ↑ ^{a b} WWF Mexico (Ed.): Illegal logging and its impact in the Monarch butterfly Biosphere Reserve . 2004 ( eco-index.org [PDF; accessed March 1, 2008]). www.eco-index.org ( Memento of the original from July 10, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
42. ↑ Urquhart (1987), p. 163ff
43. ↑ Migration & Tagging. monarchwatch.org, accessed March 2, 2008 . 
44. ^ Monarch Grove Sanctuary - Every Year, Over 25,000 Monarchs Overwinter in Pacific Grove. (No longer available online.) City of Pacific Grove, 1998, archived from the original on February 28, 2008 ; Retrieved February 19, 2008 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
45. ↑ Oberhauser & Solensky (2004), Chapter 22, pp. 177ff
46. ↑ Oberhauser & Solensky (2004), Chapter 26, p. 219
47. ↑ ^{a b} G. W. Ramsay: Overwintering swarms of the Monarch butterfly ( Danaus plexippus (L.)) in New Zealand . In: New Zealand Entomologist (Ed.): New Zealand Entomologist . tape 3 , no. 3 , 1964, pp. 10–16 ( ento.org.nz [PDF; accessed March 2, 2008]). www.ento.org.nz ( Memento of the original from October 23, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
48. ↑ ^{a b} Oberhauser & Solensky (2004), Chapter 20, p. 151ff
49. ^ Shawna Stevens, Dennis Frey: How The Other Half Lives - Monarch Population Trends West Of The Great Divide. (PDF; 137 kB) Biological Sciences Department, California Polytechnic State University, July 23, 2004, p. 3 , accessed on August 14, 2008 (English). 
50. ↑ ^{a b c d} Reduced numbers of monarch butterflies overwintering in Mexico during the 2004-2005 season: evidence, possible causes and recommendations. (PDF; 130 kB) Informally Constituted Monarch Butterfly Scientific Advisory Committee (ICMBSAC), accessed on September 11, 2008 . 
51. ↑ La migración de la mariposa Monarca en riesgo de desaparecer. WWF Mexico, accessed January 14, 2014 (Spanish). 
52. ↑ ^{a b c} Milkweed Butterflies, p. 97
53. ↑ Biological control - United States Patent 4425331 - A biologically pure culture of the microorganism Micrococcus pseudoflaccidifex, ATCC No. 31970, which is capable of producing death in insects by mechanisms associated with wilt disease. on-line
54. ↑ Catherine A. Bradley, Sonia Altizer: Parasites hinder monarch butterfly flight: implications for disease spread in migratory hosts . In: Ecology Letters . tape 8 , no. 3 . Blackwell Publishing, Mar 2005, ISSN  1461-023X , pp. 290-300 .
55. ^ Karen Oberhauser, OR Taylor, Sonia Altizer, Danel Vickerman: Biology / Parasite Control: Ophryocystis elektroscirrha. monarchwatch.org, accessed March 2, 2008 . 
56. ^ Karen Oberhauser, Ilse Gebhard, Charles Cameron & Suzanne Oberhauser: Parasitism of Monarch Butterflies (Danaus Plexippus) by Lespesia Archippivora (Diptera: Tachinidae) . In: University of Notre Dame (Ed.): The American Midland Naturalist . tape 157 , no. 2 , April 2007, ISSN  0003-0031 , p. 312–328 ( mlmp.org [PDF; accessed March 3, 2008]).
57. ↑ Oberhauser & Solensky (2004), Chapter 6, p. 47ff
58. ^ Corinne H. Watts: Predation of monarch butterfly larvae by ants . In: New Zealand Entomologist (Ed.): The Weta . tape 22 , no. 1 , 1999, p. 21–21 ( ento.org.nz [PDF; accessed March 2, 2008]). www.ento.org.nz ( Memento of the original from October 19, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
59. ↑ Urquhart (1987), p. 165
60. ↑ Lincoln P. Brower & William H. Calvert: Foraging Dynamics of Bird Predators on Overwintering Monarch Butterflies in Mexico. (GIF) In: Evolution. 1985, p. 852 , accessed on September 5, 2008 (English). 
61. ↑ Linda S. Fink, Lincoln P. Brower, Robert B. Waide & Paul R. Spitzer: Overwintering Monarch Butterflies as Food for Insectivorous Birds in Mexico. (GIF) In: Biotropica. 1983, p. 151 , accessed September 5, 2008 (English). 
62. ↑ Lincoln P. Brower, B. Elizabeth Horner, Melanie A. Marty, Christine M. Moffitt & Bernardo Villa-R .: Mice (Peromyscus maniculatus, P. spicilegus, and Microtus mexicanus) as Predators of Overwintering Monarch Butterflies (Danaus plexippus) in Mexico. (GIF) In: Biotropica. 1985, p. 89 , accessed on September 5, 2008 (English). 
63. ↑ Milkweed butterflies, p. 81
64. ↑ Urquhart (1987), p. 145
65. ^ Steven M. Reppert and Jacobus C. de Roode: Demystifying Monarch Butterfly Migration. In: Current Biology. Volume 28, No. 17, pp. R1009 – R1022, 2018, doi: 10.1016 / j.cub.2018.02.067 .
66. ↑ Urquhart (1987), pp. 5f
67. ^ Markus Kappeler: Monarch butterfly - Danaus plexippus. 1998, accessed February 19, 2008 . 
68. ↑ Monarch. (No longer available online.) In: Species at risk. Canadian Wildlife Service March 2, 2008, archived from the original April 7, 2006 ; accessed on March 2, 2008 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
69. ^ Q&A: Bt Corn and Monarch Butterflies. United States Department of Agriculture - Agricultural Research Service, April 29, 2004, accessed September 10, 2008 . 
70. ↑ A volatile upswing. WWF Germany , March 1, 2016, accessed June 30, 2016 . 
71. ↑ Mexico: Researchers fear monarch butterflies. In: Spiegel Online. Retrieved June 30, 2016 . 
72. ↑ More Than Monarchs ( Memento from January 9, 2010 in the Internet Archive )
73. ↑ Mexico: Second Butterfly Protector Murdered , AFP , February 4, 2020: https://www.afp.com/en/news/826/second-mexican-butterfly-conservationist-found-dead-doc-1op2012
74. ↑ Blanca Xiomara Mora Alvarez, Rogelio Carrera-Treviño & Keith A. Hobson: Mortality of Monarch Butterflies (Danaus plexippus) at Two Highway Crossing “Hotspots” During Autumn Migration in Northeast Mexico In: Frontiers Ecology and Evolution, 2019 doi : 10.3389 / fevo .2019.00273
75. ↑ Clare Brown, Karen Brown, Jane Stevenson Day: Karen Brown's Mexico . Karen Brown's Guides, 2006, ISBN 978-1-933810-10-2 , pp. 190 .
76. ↑ WWF: Monarch butterflies arrive in Mexico for winter hibernation on November 3, 2005
77. ↑ http://www.indieflix.com/Films/PapalotzinFlightoftheMonarchButterfly
78. ↑ http://www.whosyourmama.org/Films2008.htm

This article was added to the list of excellent articles on November 15, 2008 in this version .