Oleander hawkers
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Oleander hawk ( Daphnis nerii ) |
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| Daphnis nerii | ||||||||||||
| ( Linnaeus , 1758) |
The oleander swarm ( Daphnis nerii ) is a butterfly ( moth ) from the family of swarms (Sphingidae), which is primarily native to the tropics and subtropics of the ancient world. It also flies to Europe as a migratory butterfly and, due to its wingspan of up to 12 centimeters, is one of the largest swarmers to be found here. Unlike the skull swarms and line swarms that fly in just as far from the south , the species is a very rare guest north of the Alps. Because of its splendid coloring, it is counted among the most impressive hawk species.
features
butterfly
The male moths reach a wingspan of 70 to 100 millimeters, the females are slightly larger with 95 to 120 millimeters. The wing outline does not differ from that of other species of the genus and is entire, the wing tip is pointed. The wings are dominated by a pattern that is olive green to green in fine gradations, whereby the temperatures during the pupal rest have an influence on the development and intensity of the color tones of the butterfly. At temperatures around 21 ° C, a strong green is predominantly developed, at high temperatures above 26 ° C, on the other hand, an olive green develops. The pattern consists of curved green spots bordered by differently colored cream-colored to pale pink-red bands, the color of which also varies. A dominant band from the base of the wing to the outer edge of the forewing is usually tinted more intensely pink. Between the middle and the inner corner of the forewings there is a dark brownish to blue-violet spot. The hind wings are mostly colored like this one. The part that is not covered by the forewings in the rest position and a more or less extensive area along the outer edge of the wing, on the other hand, show the same green coloration as the forewings. In the rear half of the wing there is a fine, curved, cream-colored band. In the forma nigra , the complete green color of the butterflies is replaced by black tones.
The thorax is hairy green, with the green color becoming broader towards the front and giving way to a cream-colored, hairy triangle in the middle, the base of which ends with the rear end of the metathorax . The abdomen is similar in color and pattern to the forewings. A distinctive, light-colored band connects the two intensely colored bands of the forewings. The legs , like the approximately 14 to 17 millimeters long, thread-like antennae, are creamy yellow.
egg
The eggs of the oleander hawker are light green, almost spherical and have a very finely grained surface. With a height of 1.5 millimeters and a width of 1.25 millimeters, they are disproportionately small in relation to the size of the adult butterfly.
Caterpillar
The caterpillars reach a body length of 90 to 130 millimeters. When hatched, they are three to four millimeters long, bright yellow and have a proportionally very long, thin, dark-colored anal horn . Shortly after starting to eat, the color begins to change. By the time they first molt, the caterpillars reach a length of five to eight millimeters and have changed their color from green-yellow to bluish-green. Your anal horn is now about 2.5 millimeters long and colored black, the spiracles are also black, the thoracic legs pink. The last third of the anal horn has a cap-shaped bulge which is unusual for hawk caterpillars and which only disappears in the penultimate caterpillar stage.
Before the second molt, the caterpillars have a body length of 8.5 to 15 millimeters and a light bluish green color. The two light, dark-lined eye spots are already recognizable on both sides of the third thoracic segment . The fourth segment has none, the eight following segments each have two to six small, bright, round points. The 4.5 to 4.8 millimeter long anal horn has one or two light bumps at the tip, from which hairs arise.
During the third stage of the caterpillar, the now 20 to 25 millimeter long body of the animals turns green to yellow-green, the two pairs of eye spots on the third thoracic segment are large and have a bluish edge. On the other segments, small, blue-rimmed bright points form a continuous chain, with the exception of the last segment. The anal horn, which is now around seven millimeters long, often only has a white tip from this stage.
After the next molt, the caterpillars reach a body length of 26 to 40 millimeters. They are also colored green to yellow-green, but at this stage a brownish color can also develop. The two pairs of eye-spots on the third thoracic segment are now additionally bordered dark on the outside and occasionally merge. A yellow longitudinal line runs along the sides of the body, above which white points are scattered and under which the small white, blue-rimmed points sit in a row. The first half of the thin, 8.5 to 9.5 millimeter long anal horn is now colored yellowish white, the second is pure white or colorless.
In the fifth and last caterpillar stage, the animals reach the length described at the beginning. The basic color is now green or brown, with the back being a little darker. Occasionally the back has a pink sheen. A white longitudinal line runs on both sides of the back, with a bluish shimmer on the belly side. Within this blue area there are lined up, circular, white-colored and blue-edged points. In addition, there are additional, unedged white dots above the white longitudinal line. On each side of the back on the third thoracic segment there are two white, blue and black-edged eye spots, which mostly merge more or less into one another. The clumsy anal horn, now only four to five millimeters long, is orange and has a black tip. It is puffy and curved back and down. The spiracles are black. The thoracic legs are reddish brown to bluish, the abdominal legs have the basic color of the body. Sometimes the basic color of the caterpillars is bronze in the last stage, with the first body segments being pink. The other characteristics are then identical to those of the other caterpillar stages. You can also rarely find amber or pale ocher yellow caterpillars with purple eye spots.
Doll
Numerous body details of the later butterfly can be seen well on the 60 to 75 millimeters long, slim pupa . The head, thorax, wing sheaths, sides and abdomen of the abdomen are pale orange, the back of the abdomen is red-brown in color and has black speckles. The wing sheaths also occasionally have such speckles. The surface of the pupa is glossy, the head, thorax and wing sheaths are smooth, the abdomen is coarsely grained on the back, with the 12th to 14th segment also being tightly grained on the belly. These notches form uneven lines, these run diagonally on the stomach. The unrolled proboscis can be seen as a black line along the head and thorax. There is also a slightly wider black stripe on the back of the second to fourth body segment. The small, straight and conical Kremaster is black and ends in two blunted teeth. The stigmas are also black and each is surrounded by a black spot. The head of the doll is broadly rounded; the shoulders are not prominent. The compound eyes are also easily recognizable and have a crescent-shaped dark mark. The antenna sheaths are slightly shorter than the front legs.
Similar species
The oleander swarm can be confused with Daphnis hypothous from India and Southeast Asia , which is very seldom seen as a migratory butterfly in the west of the Palearctic . D. hypothous has a very similar pattern, but with a black base color, which is why the forma nigra in particular is very similar to it. A definite distinguishing feature is a white round spot on the tip of the forewing, which the oleander hawk lacks.
Way of life
The nocturnal oleander swarms fly after sunset until before sunrise. They suck nectar from various plants, such as from tobacco ( Nicotiana ), petunias ( Petunia ), honeysuckles or honeysuckle ( Lonicera ), soap herbs ( Saponaria ) and miracle flowers ( Mirabilis ), with about 0.4 to 0.8 milliliters per foraging Nectar to be absorbed. In addition to nectar, water is also sucked in by dew and raindrops. Unlike the similar D. hypothous, the oleander hawk is rarely attracted by artificial light.
During the day, the moths either rest on firm ground or hang well camouflaged between foliage. The head is drawn in, the thorax and abdomen are stretched away from the ground. If the temperatures are favorable, the moths are very frightened and, if disturbed, also fly during the day. The life cycle of the species is adapted to the climatic conditions and day lengths in the tropics. They prefer temperatures just under 30 ° C all year round and ideally 12 hours of sunshine and a maximum of 14.5 hours per day.
Migratory flights and flight times of the moths
The oleander hawk is a migratory butterfly that does not migrate anywhere in the world, which suggests that the migratory instinct is not genetically determined but is conditioned by environmental factors. This can be seen well in the introduced population in Hawaii . This was able to establish itself within just two years on the island chain, where ideal temperatures around 28 ° C and day lengths between 12 and a maximum of 14.5 hours prevail. A settlement would not have been successful under environmental factors that cause migration, as the archipelago is geographically isolated and the distance to the mainland is too great, so that the migrating moths could no longer return and the population would die out.
Between 14 and 14.5 hours of sunshine per day is the critical photoperiod that triggers the caterpillars to determine whether the later moths remain sedentary or migrate. This is due to the fact that in regions with a longer day length, for example from May 20 around the 25th parallel in Saudi Arabia , daytime temperatures of over 30 ° C are reached, which are critical for the pupae lying on the open ground . The eggs that hatch there in June are delayed due to the longer duration of the day. The moths migrate further north from the warm regions, their eggs mature in the meantime and can then be laid in the cooler regions, for example in the Mediterranean region . The next-generation caterpillars growing there are also exposed to days of more than 14.5 hours, but survive due to the milder temperatures and so start their return flight south. In these moths, the egg maturation is also delayed, so that the eggs can be laid in their southern home after arrival.
North of the Alps, however, the moths face the following problems: The day length increases to 18 and more hours and the soil temperatures are not continuously above 25 ° C. In adults who develop from the eggs laid there - which is only possible in hot years - egg maturation is delayed to such an extent that it is unlikely that their eggs will develop at all. It is also not known whether the return flight of these animals will be successful.
The oleander hawk flies in its tropical distribution area all year round in continuously successive generations. In the southern Mediterranean region, North Africa, the Middle East to Afghanistan, the species flies from May to September, with four to five generations, which mostly overlap, are trained. In southern Europe, two generations fly in as migrant butterflies between June and August, further north it is only one from June to September, with their caterpillars hatching from July to September.
In Hong Kong, two generations fly from October to February and rarely also in May, in Japan they fly in the south on the Ryūkyū Islands from May to November, in the north on Kyūshū they fly in from September to November.
Mating and laying eggs
The mating, in which the partners are coupled to each other with the body in opposite directions on the abdomen, as is usual with swarmers, takes place relatively quickly and lasts a maximum of about four hours. Occasionally, however, the couple stays connected until morning. In the following three days, the females lay an average of 100 eggs individually on the top and bottom of the food plants, with a maximum of around 300 eggs. They do this on the leaves of young, individually, preferably protected bushes of the food plants. Often plants are chosen for laying eggs that are at the foot of slopes, near houses or near trees in a clearing. The female often flies around the plant several times before laying the egg in flight in a pendulous motion.
Food of the caterpillars
Most of the food plants of the caterpillars belong to the family of the dog poison plants (Apocynaceae): The caterpillars feed mainly on oleander ( Nerium oleander ), also on periwinkles ( Vinca ), Amsonia ( Amsonia ), silk plants ( Asclepias ), desert roses ( Adenium ), wax trees ( Carissa ), Tabernaemontana , Thevetia , room evergreen ( Catharanthus ); but also on vines ( Vitis ), gardenias ( Gardenia ), jasmine , star jasmine ( Trachelospermum ), rhazya , morning glory ( Ipomoea ), and probably on mangoes ( Mangifera ). When rearing, the caterpillars also take on oval-leaved privet ( Ligustrum ovalifolium ). Reinhardt and Harz also mention lilacs ( Syringa ) and privet ( Ligustrum ) and, rarely, Cornelian cherry ( Cornus mas ) and real walnut ( Juglans regia ) as food plants.
The caterpillars can also be found mainly on oleanders as far as Southeast Asia, and also on Adenium obesum and the rose-colored Catharanthe ( Catharanthus roseus ). The food plants of the caterpillars in China and Taiwan are not yet known.
development
Before hatching, the eggs have a yellow tinge. The nocturnal caterpillars hatch after an average of 12 days, in hot weather after about five days. The egg shell is eaten immediately after hatching, after which the animals immediately eat the food plants. They are very voracious, larger caterpillars can eat twice their weight of leaves per day. The caterpillars can also crawl backwards and move their horn up and down regardless of their locomotion. Young animals usually move jerkily. They are usually found sitting open at the ends of young side shoots, older caterpillars tend to feed in the branch tips, where they stay further down on the branches with increasing size. First of all, all existing flowers are always eaten, otherwise young and medium-old leaflets as a whole. With older leaves, only the outer edge is pitted. Gravimetrically , the feeding behavior of the caterpillars could be examined in detail on caterpillars bred in the laboratory. Young leaves have a higher water content, and caterpillars can also eat the most of them and convert them into energy. The strong growth of the caterpillars feeding on young leaves is therefore not only linked to the better energetic usability of the leaves, but also to the water content and the higher absorption capacity. The water content in the body of these caterpillars is higher than that of caterpillars that feed on older and less watery leaves, as most of the water is absorbed by the leaves. The main excretion is through feces. That of caterpillars on older leaves is significantly drier than that of caterpillars on young leaves, since the former utilize water much better and can absorb it in their intestines. Nitrogen is another important factor in animal growth. Middle-aged leaves have the highest nitrogen content, which is why they are also eaten with pleasure.
The caterpillars are well camouflaged by their color and imitation of leaves and are difficult to spot. However, they reveal themselves through their approximately five millimeter long excrement (ball of feces ), which can be found on the ground around the plant. Older caterpillars often climb down to the base of the plants during feeding breaks and hide under stones or plant material during the day. If they stay on the plants, they will sit on the underside or on the stem of a leaf. You will then rest with your body stretched out and your thorax straightened with your head slightly lifted. If you disturb them, try to imitate a leaf by stretching your body. If the disorder persists, arch your back outward and bend your head down so that it almost touches the thoracic legs. This posture allows you to see the eye spots particularly well. This scares off predators, as the size of the eyes suggests a much larger animal ( mimicry ) and also warns of the toxicity of the caterpillars. The food plants mainly contain highly toxic cardenolide glycosides , which could also be detected in the body of the caterpillars and their excretions. However, Kitching (2000) quotes Rothschild (1973) who was not yet aware of this. The caterpillars can also choke poisonous stomach contents when threatened.
After moulting, the caterpillar eats the stripped exuvia . The last stage of caterpillars lasts an average of eleven days, with the caterpillar beginning to turn dark olive brown to chocolate brown, purple or orange-red from the sixth day onwards. The caterpillars then still show the rest of their markings, only the large eye-spots occasionally turn completely black. On the seventh day, the animals stop eating and the body changes color by the eighth day at the latest. On the tenth day, the caterpillar enters the prepupal stage and progressively contracts the body. On the last day it leaves the food plant and looks for a suitable place to pupate. During this search, it secretes slimy intestinal contents.
Pupation
Pupation does not take place in, but directly on the ground, often in a flat depression; from time to time the caterpillars pupate under moss. You create a loose web of yellow to brown silk, in which some plant material is also incorporated. The creation of the web and pupation takes about three days, after a further two days the initially yellow-colored pupal skin has its actual color and its slightly transparent shell is hardened. The doll lies freely in its web and moves its abdomen when disturbed. The adults hatch after three to six weeks. The pupa cannot tolerate the cold and dies at temperatures below 10 ° C, which is why pupae overwintering in Europe only very rarely survive in the south.
The moths usually hatch between 10 p.m. and 11 p.m., but do not fly until the next dawn at the earliest. Most animals start their first flight the following evening.
distribution and habitat
Overall spread
The year-round distribution area of the animals extends from the southern Mediterranean region, North Africa , the Middle East , Afghanistan , India and Sri Lanka , east to tropical Southeast Asia and the Philippines . They can also be found in tropical Africa . The limit of the year-round distribution is not clear in Europe, but the species occurs permanently in favorable locations on Sicily , Crete and Cyprus . If the conditions are ideal for several consecutive years, other parts of these islands and also the south of Italy and Greece are settled. However, these deposits disappear after a winter that is too cold for the pupae.
Until a few years ago, the species was rarely known in southern China and Taiwan, but populations in these areas are now stable, for example in Hong Kong . The oleander hawk was introduced to Hawaii by humans in 1974, and Guam is now also settled.
In Europe, the species occasionally flies in in the summer and can also penetrate far into Scandinavia. However, it is a very rare guest in the north and only occurs very rarely in Central Europe. Years with numerous butterfly observations and also caterpillar finds from large parts of Germany are known from historical times, but in an average year only a few individuals are observed in Germany. The moths also make migratory flights to central South Asia and the southern parts of Japan.
habitat
The oleander hawk is found preferentially on dry rivers, in oases and on temperature-favored slopes wherever oleander grows sporadically. Places where the plants are found in large numbers are more likely to be avoided. Since oleander rarely grows north of the Alps in Europe, more than 100 caterpillars can be found here on individual plants.
Specialized enemies and threat
So far, three specialized parasitoids of the caterpillars of the oleander hawk are known. In the western range it is the brackish wasp Cotesia saltator , in the eastern range it is the two caterpillar flies Compsilura concinnata and Exorista sorbillans . The females of these parasitoids lay their eggs on the caterpillars, in which the hatched larvae then develop. Pupation usually takes place on the outside of the previously dead caterpillars.
Due to its wide distribution and frequency, the oleander hawk is not endangered.
Naming and systematics
The oleander hawk was first described by Carl von Linné in 1758 in the 10th edition of the work Systema Naturae as Sphinx nerii :
" S. [phinx] alis subangulatis viridibus: fasciis variis pallidioribus saturatioribus flavescentibusque. … Habitat in Nerio. "
" S. [phinx] with slightly angular, green wings: with different, paler and deeper yellow bands. ... Lives on oleander. "
The species name is derived from the Latin generic name of the most important food plant of the caterpillar, the oleander ( Nerium oleander ).
In 1819 Jacob Hübner described the genus Daphnis to which the species belongs today. The genus contains about ten species common in the tropics and subtropics of the Old World . This is classified with currently 77 other genera within the subtribe Macroglossia, which together with the sister taxon Choerocampina form the tribe Macroglossini . The position of the subfamily Macroglossinae next to the other two subfamilies of the hawkmoths is well founded, but the monophyly of all tribe and subtribe within this is uncertain, except that of the Choerocampina.
Synonyms
- Sphinx nerii Linnaeus, 1758, Syst. Nat. (Edn 10) 1: 490
- Deilephila nerii bipartita Gehlen, 1934, Bull. Mus. r. Hist. nat. Belg. 10 (3): 2
- Daphnis infernelutea Saalmüller, 1884
swell
Individual evidence
- ^ A b Rolf Reinhardt, Kurt Harz: Wandering Schwärmerarten. Skull, curling, oleander and line swarmers. Die Neue Brehm-Bücherei Vol. 596, Westarp & Spectrum, Magdeburg, Heidelberg, Berlin and Oxford 1996, ISBN 3-89432-859-2
- ↑ a b c d e f Sphingidae of the Western Palaearctic. AR Pittaway, accessed March 24, 2008 .
- ↑ a b c d Sphingidae of the Eastern Palaearctic. AR Pittaway, accessed March 24, 2008 .
- ↑ K. Murugan, Ancy George: Feeding and nutritional influence on growth and reproduction of Daphnis nerii (Linn.) (Lepidoptera: Sphingidae) . Journal of Insect Physiology, Volume 38, Issue 12, December 1992: pp. 961-967
- ↑ Fumiko Abe, Tatsuo Yamauchi, Kazuo Minato: Presence of cardenolides and ursolic acid from oleander leaves in larvae and frass of Daphnis nerii . Phytochemistry, Volume 42, Issue 1, May 1996: pp. 45-49
- ^ M. Rothschild: Secondary plant substances and warning coloration in insects. In: HF van Emden (Ed.): Insect / plant relationships. Symposia of the Royal Entomological Society of London 6: 59-83.
- ^ Ian J. Kitching, Jean-Marie Cadiou: Hawkmoths of the World. An Annotated and Illustrated Revisionary Checklist (Lepidoptera: Sphingidae). Cornell University Press, New York 2000, ISBN 0-8014-3734-2
- ↑ Heiko Bellmann : The new Kosmos butterfly guide. Butterflies, caterpillars and forage plants. Franckh-Kosmos, Stuttgart 2003, ISBN 3-440-09330-1 .
- ↑ Günter Ebert: The Butterflies of Baden-Württemberg Volume 4, Moths II (Bombycidae, Endromidae, Lemoniidae, Saturniidae, Sphingidae, Drepanidae, Notodontidae, Dilobidae, Lymantriidae, Ctenuchidae, Nolidae), Ulmer Verlag Stuttgart 1994, ISBN 3-8001-3474 8th
- ↑ Daphnis nerii. Sciense4you, accessed May 14, 2008 .
- ^ Butterflies and Moths of the World, Generic Names and their Type-species . Natural History Museum, accessed March 29, 2008 .
- ↑ Jerome C. Regiera, Charles Mitter, Timothy P. Friedlander, Richard S. Peigler: Phylogenetic Relationships in Sphingidae (Insecta: Lepidoptera): Initial Evidence from Two Nuclear Genes . Molecular Phylogenetics and Evolution, Volume 20, Issue 2, August 2001: pp. 311-316
- ↑ Daphnis nerii (Linnaeus 1758). Fauna Europaea, Version 1.3, April 19, 2007 , accessed on January 3, 2008 .
literature
- Günter Ebert : The Butterflies of Baden-Württemberg Volume 4, Moths II (Bombycidae, Endromidae, Lemoniidae, Saturniidae, Sphingidae, Drepanidae, Notodontidae, Dilobidae, Lymantriidae, Ctenuchidae, Nolidae). Ulmer Verlag, Stuttgart 1994, ISBN 3-8001-3474-8
- Manfred Koch : We determine butterflies. Volume 2: Bears, Spinners, Swarmers and Drills in Germany. 2nd, expanded edition. Neumann, Radebeul / Berlin 1964, DNB 452481929 .
- AR Pittaway: The Hawkmoths of the western Palaearctic. Harley Books, 1993, ISBN 0-946589-21-6
- Rolf Reinhardt, Kurt Harz : Migratory swarmers. Skull, curling, oleander and line swarmers. Die Neue Brehm-Bücherei Vol. 596, Westarp & Spectrum, Magdeburg, Heidelberg, Berlin and Oxford 1996, ISBN 3-89432-859-2
- Hans-Josef Weidemann, Jochen Köhler: Moths. Weirdos and hawkers. Naturbuch-Verlag, Augsburg 1996, ISBN 3-89440-128-1 .
