Ant maids

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Ant maids
Spotted-winged ant damper (Euroleon nostras)

Spotted- winged ant damper ( Euroleon nostras )

Systematics
Class : Insects (Insecta)
Subclass : Flying insects (Pterygota)
Superordinate : New winged wing (Neoptera)
Order : Reticulated winged (Neuroptera)
Subordination : Myrmeleontiformia
Family : Ant maids
Scientific name
Myrmeleontidae
Latreille , 1802

The ant maids (Myrmeleontidae) form a family within the netwings , an order of insects . There are around 2000 species worldwide, eleven of them live in Central Europe. More generally known than the nocturnal full insects are the larvae, the ant lions , because of the special prey method of some species. In the English-speaking world, the name antlion (ant lion) is therefore also used for the insect in all stages of development; there is no English equivalent for "ant maiden".

Systematics

The system within the net wing has not yet been finally clarified. It is generally accepted, however, that the ant maids form a monophyletic group that is in sister group relationship with the butterfly-like (Ascalaphidae). These two together with the families Nymphidae , Nemopteridae and Psychopsidae form the group Myrmeleontiformia .

Within the ant maid, the following subfamilies were initially distinguished:

In the meantime, however, more (around ten) groups are usually placed in the rank of subfamily.

distribution

Ant youngsters are distributed over all continents (except Antarctica), but concentrate on the desert and semi-desert areas in Africa and Asia, partly also in South America and Asia. Preferred habitats are usually characterized by extreme drought, and often also an extensive lack of vegetation. Some species also live in forests, but here too they prefer light, dry forests.

Central European species

Dendroleontinae:

Widespread in southern Central Europe, detected as far as Asia. It inhabits light, dry, warm deciduous forests.

Acanthaclisinae:

Largest native species, widespread throughout the Mediterranean, in large parts of Central Europe to the Polish Baltic coast.

Myrmecaelurinae:

In the entire Mediterranean area, spread to southwest Central Europe, mainly dry fallow meadows settled.

Myrmeleontinae:

Populates all of Europe except the British Isles, large parts of Asia, one of the most common species in Central Europe.
Smallest native species of the genus, one of the most common species in Europe, only very locally in the south-east due to the high heat requirements in Central Europe.
Detected only sporadically in Northern and Central Europe, also widespread in large parts of Asia to Japan. Above all populated sparse pine forests and dunes.
Populates large parts of Europe as far as Asia and the Mediterranean, one of the most common species in Central Europe, but limited to the lowlands.

Nemoleontinae:

Sometimes extremely common in southern Europe, it only reaches Central Europe in southern Switzerland.
The relatively large species has strikingly dark brown spotted wings and lives in Central Europe only in isolated heat islands.

Glenurinae

It is one of the most common species in Southeastern Europe, it only reaches Central Europe in Slovakia. It prefers very dry fallow meadows.
Small species, one of the more common in Europe, only reaches Central Europe in southern Switzerland and eastern Austria.

Hazard and protection

The ant damper species native to Central Europe are consistently rare species. Only two species are regularly found in suitable biotopes, but these too are often affected by the destruction of their habitats. Usually a very small sun-exposed and rain-protected area is sufficient for the larvae of Myrmeleon formicarius and Euroleon nostras to build their funnels, for example under cut tree trunks or at the foot of south -exposed house walls. The other funnel builders prefer open terrain. To protect them, the preservation of appropriate habitats, e.g. B. Inland dunes , necessary before encroachment or sealing.

The other species are rarely found in Central Europe and usually have very special requirements for the biotope conditions. Dendroleon pantherinus is the only native tree-dwelling species that needs deciduous forests with deadwood structures .

anatomy

Common ant damsel ( Myrmeleon formicarius ) with wings at rest

In their physique, the ant maids are similar to the dragonflies , they have in common with them the long, evenly narrow physique and two pairs of largely identical skin wings. The similarities are only of a superficial nature, ant maids do not have the modified structure of the dragonfly's thorax , but, as new-winged birds, have the wing joint that allows them to fold their wings backwards. A striking difference is also the clearly visible antennae , which are club-shaped in the European species .

  • Size: The ant maids are the largest species of reticulated winged flyers, some representatives of the genus Palpares in tropical Africa have a body length of 60 mm with a wing length of 80 mm, an Arabian species, however, only reaches a wing length of 10 mm. The European species have a body length of up to 50 mm and a wing length of 20 to 60 mm.
  • Color: As an adaptation to the nocturnal way of life, the animals are mostly inconspicuous and very uniformly colored, predominantly red-brown to black-brown. They usually have dark markings on the head and thorax. The wings are mostly colorless and transparent, but often have small or larger brown spots.
  • Head: Ant maids have downward-pointing mouthparts (orthognath), conspicuously large complex eyes and no point eyes . The antennae are shorter than those of the rest of the reticulated winged birds and mostly thickened like a club at the end. Also noticeable are the long lip buttons with the club-shaped end member in which a sensory organ is located.
  • Chest: The thorax consists of three largely identical segments. The legs are relatively short and thin and have no particular deviating formations. The tarsi are five-limbed, the last and claw-bearing limb is the longest.
  • Wings: The wings are elongated and mostly narrow to very narrow. The front edge is strongly rounded to the usually clearly formed tip, the rear edge runs straight or slightly bulged here. The front and rear wings are designed very similarly and do not have a coupling mechanism . The ample veining of the wings provides important features for the systematic division of the family. In some species, the males have a small button-like appendage at the base of the hind wings, the axillary pads , which probably serve as odor organs.
  • Abdomen: The abdomen of the ant maid is elongated and consists of ten segments, of which nine in the male and seven in the female are fully developed. The tenth back segment (ectopectus) is designed in pairs in the male and can be designed very differently, also greatly elongated. In some species, the males also have stalked hairbrushes on the sides of the fifth, sixth or seventh abdomen segment, which are used to spread attractants.

In some points the species of the Palparinae show deviations in body structure: The wings are significantly wider than that of the Myrmeleontinae, often also darkly tinted, overall the animals show a greater variety in coloration. The thorax is broader and more stocky, especially the first segment, the thighs are significantly thickened and the tarsi are shorter.

Stages of development

According to the current state of knowledge, the development is largely the same for all ant species, before the adult stage they all go through an egg stage, three larval stages and the pupal stage.

Ant maiden - panel from “Insect amusement” by Rösel von Rosenhof

egg

Little is known about egg laying, the number of eggs laid per female is likely to be very low. The eggs are elongated and coated with a secretion , which means that they do not stand out from the ground because of the adhering particles. They are placed individually in suitable locations, usually in the early evening and the first half of the night.

larva

The larvae have always been known as "ant lions", especially because of the prey-catching method of the funnel-building species.

The body of the larvae is diamond-shaped and compact, the head is square to heart-shaped and is determined by the powerful, curved jaws at the front . In outline, the first two pairs of legs stand out from the body in addition to the head. In the first larval stage, almost half of the body length is on the head including the jaws.

The abdomen consists of ten segments, which are laterally provided with bristle humps. The tenth segment is formed as an extendible spinning tube and is normally retracted into the eighth and ninth segments. At the end of the larval period, the cocoon spinning thread emerges from the spinning tube and is formed from a secretion from the Malpighian vessels .

The structure of the ant lion's legs is quite different according to the way of life. While the first pair of legs is usually relatively inconspicuous, the second protrudes sideways far below the body. The two front pairs of legs have two-part tarsi, the rear one-part, which are fused with the tibia.

Doll

At a depth of a few centimeters in the sandy soil, the adult larva begins to spin the cocoon by first putting on a protective roof to catch sand that slides down. A spherical outer cocoon is then created by rotating movements, in the threads of which sand particles are also incorporated. Finally, the inner, parchment-like layer of silk is applied that surrounds the prepupa .

The prepupal phase lasts a few days to weeks, after which the prepupa sheds its skin into a pupa. The pupa is initially colorless to whitish and turns reddish-brown before hatching. The pupa opens the cocoon on the top and leaves the cocoon. Then the imago slips out of the pupa shell, digs itself to the surface of the earth and climbs on nearby plants to unfold the wings and harden the cuticle .

  • larva

  • Cocoon in the sand

  • last larval skin

  • hatched imago

Way of life

The behavior of the funnel-building larvae is undoubtedly the best known and best researched phenomenon regarding the way of life of the ant maid. In contrast to this, the way of life of the adult animals as well as the larvae, which do not build funnels, is poorly known.

Lifestyle of the adults

The adults of most species are nocturnal, some, often brightly colored species in the tree-free zones are also active during the day, e.g. B. the genera Palpares in Africa or Periclystus in Australia. During the day most species sit hidden in the vegetation, mostly flat on vertical blades of grass. The wings are folded like a roof over the abdomen, the antennae are laid flat against the ground. In hot sandy areas, the ant maids usually stay at a height of 10–40 cm, where they are least exposed to the heat radiation of the subsoil on the one hand and to the wind on the other. Nevertheless, they also observe their surroundings during the day, always ready to be blown up in the event of a disturbance and to settle down again at a location several meters away.

Night activity begins at dusk and reaches its maximum before midnight. The activities consist of longer search flights on the one hand and stationary foraging or mating flights on the other.

food

The diet of the ant maid consists mainly of insects. During the nocturnal flights, the animals could be observed catching small butterflies , which they hold on to with their forelegs and perch on the nearest plant to chew their prey, leaving the wings. Sometimes they also take in nectar and pollen from flowers , some species seem to feed exclusively on bee pollen. The long spurs on the tibia of some species are seen as auxiliary organs for prey acquisition, so the spurless species are mainly considered to be aphid eaters . Larger species such as members of the genus Acanthaclisis , however, are aggressive hunters.

Mating and laying eggs

Not much is known about the mating of the ant maids, the observations are only patchy. It is assumed that pheromones play an essential role in gendering. In many species, the males have special organs that are used to diffuse scents. Since the ant maids' intensive history of exploration, the mating has remained unnoticed for a long time as it takes place in the dark. Even Rösel von Rosenhof and RAF Réaumur and many other generations of researchers did not succeed in their lives.

It was not until 1991 that the two nature filmmakers Klaus Weißmann and Rolf Sziringer observed this behavior in the Hungarian Kiskunsager National Park . After dusk fell, they were able to take pictures of the ant maiden species Myrmecaelurus trigrammus during courtship, mating and egg-laying. During courtship, the males initially danced over the grass with their protruding, brush-like scent organs, while the females sat hidden on blades of grass, but then suddenly flew open and grabbed a male from the crowd. Since the mating took place in almost complete darkness, the brush-like organs on the abdomen that the males turned out apparently had two functions: they served both olfactory perception and as a gripping aid for the female. It is possible that the male secretes scents with these organs, which enable the female to find the male in the dark. The bracing took place in flight at a height of up to two meters. Only then did the couple rest for a short time on a blade of grass or a branch, with the female always hanging in front and the male hanging upside down. The mating lasted at most between one and two minutes for this species. Klaus Weißmann suspects that the previous generations of researchers were unable to observe in the laboratory because the containers in which they were held were too small, because the mating chain was formed in flight, for which the young ant maids needed enough space.

Weißmann and Sziringer also photographed the egg-laying of the species Myrmecaelurus trigrammus for the first time in 1991. The female shoveled a hole up to three centimeters deep with her abdomen and alternately pushed the excavated sand forward with her legs. Up to 11 eggs were laid in the hollow. The egg-laying area was then covered again with sand and stalks. After laying eggs, the females cleaned themselves and often also ate their own egg.

The native species Euroleon nostras is known to lay eggs individually or in small groups with curved abdomen in the upper sand layers of suitable biotopes between dusk and midnight.

Lifestyle of the larvae

Funnel-building species

Only around 10% of all species build the well-known trap funnels as larvae, including around 100 species of the Myrmeleontini tribe. The larvae of this group can only move backwards and are therefore practically dependent on the construction of funnels to catch prey. Other funnel-building species among the Mymecaelurini and Isoleonini do not have this restriction and can therefore alternatively pursue “normal” prey capture.

The most important requirement for the construction of the funnel is the dryness of the substrate. Other properties of the subsoil such as grain size or specific weight have little or no influence on the success of the funnel construction; slopes can also form a suitable subsoil.

The survival advantage that led to the creation of the funnel structure is likely to be that in extreme habitats, the need for movement on the hostile surface of the earth can be reduced to a minimum. The prey animals of the ant maids include a wide variety of arthropods, occasionally even snails and earthworms, so by no means exclusively ants.

Non-funnel-building species

There are considerable differences in the behavior of the ant youngsters who hunt without a funnel, but only very few observations have been made in this area. Different types of specialization have been described:

  • Ground dwellers: This probably includes most species. They often stay hidden in the litter layer of the ground and wait , sometimes for days, for approaching prey. Other species (e.g. Acanthaclisis baetica ) actively pursue their prey, which they grab and drag under the surface of the sand.
  • Tree cave dwellers: Some species, including the Dendroleon pantherinus found in Germany , hunt for insects in the sludge of old tree stumps.
  • Tree trunk dwellers: A single observation has been made of an Indian species that perches on the bark of mango trees.
  • Rock dwellers: some species sit in protected places on rocks, sometimes for a very long period of time.

lifespan

The Central European species usually have a two-year life cycle, there is an annual life cycle for Myrmeleon inconspicuus , and a three- year cycle for Myrmeleon bore . In tropical species there is no link to the seasonal rhythm. The lifespan of adult insects is estimated differently, but is usually between two and four weeks. In captivity, however, some specimens can survive for up to six weeks under ideal feeding conditions. The flight times of the Central European species are in the summer months, one of the earliest species is Myrmeleon formicarius with the maximum activity in June, one of the latest Euroleon nostras , which mainly flies in August. Some species show proterandry , i. that is, the males appear a few days earlier than the females.

Enemies and defense

Ant lions have relatively few natural enemies due to the choice of habitat and the hidden way of life. Ant lions are evidently not regarded as worthwhile prey by birds and reptiles , and no population decimation has been observed where they live together. Only a few other predators are known, but some prey can defend themselves violently, e.g. For example, large ants sometimes prey on the ant lion themselves. Instead, some species become paralyzed . Parasites that attack ant lions are known from the parasitic wasps , wasps and woolly slivers .

The adult insects are likely to be exposed to the usual predators both during the nocturnal flight time and during the day when they are resting. When disturbed, they mostly fall into a frightened position, which is characterized by wings spread out in a V-shape.

literature

  • Johannes Gepp and Herbert Hölzel (1989): Ant lions and ant maids - Myrmeleonidae. Neue Brehm-Bücherei, Volume 589, ISBN 3-89432-322-1
  • Klaus Weißmann (2008): Adventure nature film - a senseless story , Naturfilm-Verlag, ISBN 978-3-00-022720-2 , pp. 77–94

Web links

Commons : Ant dams  - Collection of images, videos and audio files