Caddis flies

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Caddis flies
Caddis fly of the species Glyphotaelius pellucidus

Caddis fly of the species Glyphotaelius pellucidus

Systematics
Sub-stem : Trachea (Tracheata)
Superclass : Six-footed (Hexapoda)
Class : Insects (Insecta)
Subclass : Flying insects (Pterygota)
Superordinate : New winged wing (Neoptera)
Order : Caddis flies
Scientific name
Trichoptera
Kirby , 1813
Submissions
schematic drawing of a caddis fly larva without a quiver
Larva from the family Limnephilidae with quiver
Quiver of a larva
Caddis fly larva in its quiver
Limnephilus rhombicus

The caddis flies (Trichoptera) form an order of insects within the new winged birds ( Neoptera) and belong to the holometabolic insects (Holometabola). With around 13,000 known species , it is the largest primarily aquatic insect order. Almost 400 species live in Central Europe . A total of 1211 species and subspecies have been recorded from Europe. The body length of the animals is between 1.5 and 40 mm, the wingspan between 3.5 and 68 mm. The smallest Central European species belong to the Hydroptilidae family (approx. 3 mm, wing length approx. 5 mm). The largest Central European species is Phryganea grandis (Phryganeidae) with 60 mm.

Anatomy of the caddis flies

A striking feature of the caddis flies are the more or less hairy wings, from which the name of this order is derived ( Greek Trichos 'hair' and Greek pteron 'wing'). These are laid in a roof-like manner on the animals' abdomen. In some species, however, these wings can be stunted or missing entirely (not in Central Europe). The forewings are usually brownish or yellowish in color (sometimes whitish or black, rarely also colored) and often spotted or patterned. The fore wings are usually longer than the hind wings. Since these are wider, their area is almost the same. In flight, the wings are connected to each other by hooks and bristles that act as a coupling mechanism and form a functional unit. Few caddis flies have scales on their wings; B. the African species Pseudoleptocerus chirindensis , similar to butterflies . The body of the caddis flies is more or less elongated. On the thorax there are three mostly long and slender pairs of legs. Long thorn-like appendages (“spurs”) on the tibia are an important feature for differentiating between families. In some families, the middle legs of the females are flattened as swimming legs (to lay eggs). The abdomen is cylindrical. At the rear end of the abdomen are the copulatory organs , which have been transformed in many ways and which are the most important feature for determining the species. On the side of the head are usually quite large and well-developed complex eyes , the 3 forehead eyes ( ocelles ) can be present or absent depending on the family. The antennae are cord-shaped and usually very long, their length can significantly exceed the length of the body. The caddis flies have leaky mouthparts , with the mandibles completely missing or rudimentary and inoperative. Large, leg-like palps are formed on the maxilla , which can sometimes be elongated like a whip. The lower lip ( labium ) can be turned out and forms a so-called haustellum. This has many small hairs (microtricha) at the front end (formed from the prementum as part of the labium), which form a system of connected canals. At the rear end they merge into a groove, the upper half of which is formed by the epipharynx (inside of the clypeolabrum) and which leads to the actual mouth opening, which is hidden inside. The house cell can be extended by increasing the pressure of the hemolymph and retracted by muscles. With it, the animals are able to suck up water and nectar through capillary forces . However, in some species the adult caddis flies do not consume any food at all (e.g. Enoicyla , Fam. Limnephilidae: lifespan of the adults here approx. 14 days). The lifespan of the winged imaginal stage is around 4 weeks for most species. In species with an imaginal diapause , it can be 5 to 6 months.

In contrast to their sister group , the order of butterflies, caddis flies have "hairy" wings and do not have scales; they lack a proboscis.

Reproduction and development

Most adult caddis flies are crepuscular and nocturnal. In diurnal species, the males often form mating swarms, the copulation of the sexual partners then takes place in the vegetation. In the Limnephiloidea, the fertilized eggs are put into the water as jelly packets (sometimes in flight), in the Rhyacophiloidea and Hydropsychoidea they are glued to plants, stones or other substrate elements with a cement substance. In the Limnephilidae and Goeridae, the females of most species lay the spawn outside the water on branches or overhanging stalks, from where it drips into the water. In some species (especially the Phryganeidae family), the female also dives under water to lay eggs and for this purpose has central and rear legs that have been specially converted into swimming legs.

An egg larva hatches from the egg, which then sheds its skin five times up to the pupal stage (5 larval stages). The head of the larvae has well-developed, biting mouthparts (mandibles). On the side of the head there are eyes made up of six individual ocelles (stemmata), similar to the eyes of beetle larvae and eyes of caterpillars. The antennae of the larvae are short. In the quiver-carrying families, there are often one to three humps on the first abdomen segment that are used to hold on. They often have finger-like or fringe-like tracheal gills on the abdomen, and occasionally also on the thorax, which support breathing. The number, shape and arrangement of the gill threads are typical of some families and genera. All caddis fly larvae have pygopodial claws (push-up claws) at the rear end to hold onto, often on elongated, leg-like appendages.

The larvae are named after the burrows, which are called quivers . These are built from a secretion that the larvae release from the labial glands on the head and with which they form a web; it corresponds to the cocoon silk of the butterfly caterpillars. Most quivers consist of substrate elements such as stones or pieces of reed, which are glued to a tube with the help of the spinning secretion. As the larvae grow, new material is added to the front end. The rear end is bitten off in many species as they grow. It is then sometimes closed with a conspicuous membrane. The shape of the quiver can be highly characteristic of a family or species, e.g. For example, the Glossosomatidae build high, arched, short “piles of stones” (like a turtle shell), the Beraeidae narrow, smooth, curved sand quivers, the Goeridae short straight quivers from coarser stones from which larger stones protrude at the sides, and some Lepidostomatidae square quivers from cut pieces of leaf. The quiver of Thremma (Thremmatidae) is cap-shaped, that of Helicopsyche is twisted like a snail shell.

However, there are also quite a few families that do not build quivers (Rhyacophilidae, Hydropsychidae, Psychomyiidae and others). The larvae of the Psychomyiidae build tunnel-shaped, sometimes branched, living tubes on the surface of stones. Other families use the spinning secretion to build drift nets to filter the water to get food. Still others are completely free.

The shape of the quiver-building caddis-fly larvae is reminiscent of butterfly caterpillars ; after the Latinized name, this larval form is sometimes referred to as "erucoid". In contrast to these, they never have ventral feet on the abdomen; most species have there, sometimes several, regular pairs of gills . Most of the free-living larvae have a more elongated shape with the head stretched forward, which has reminded some investigators of the urine insect Campodea (order Diplura); they are then called "campodeid".

The pupation occurs in the quiver or the non quiver-building species in special cocoons, usually attached to stones. The pupa stage has large, movable mandibles that serve to cut open the quiver or pupa cocoon before hatching. The doll is agile; in the case of a lack of oxygen, it performs winding movements in the quiver in order to accelerate the exchange of water. To support it, it usually has wide hair or bristle borders on the abdomen. When the pupa hatches (after a maximum of four weeks of rest) the pupa swims and crawls to the surface of the water. The winged insect hatches on the bank, clinging to stones or plants, out of the pupal skin in three to four minutes, usually at night.

Ecology and way of life of the caddis fly larvae

The larvae of the caddis flies live aquatic, with a few exceptions: the only Central European genus whose larvae live terrestrially is Enoicyla (Fam. Limnephilidae). The vast majority of them are inhabitants of the rivers, where they are among the most important and most species-rich inhabitants of the macrozoobenthos , in streams they are usually the most individual and species-rich colonists together with or just after the two-winged species. The number of species in a stream (not polluted by wastewater) is around ten in structurally poor lowland streams; in mountain streams it can exceed fifty species in a short stretch of water. The individual species are mostly specialized in certain sections of water, with all sections from springs and source brooks ( Krenal ) to brooks ( Rhithral ) to rivers ( Potamal ) being populated in a species-rich manner . Medium-sized streams and small rivers are particularly rich in species.

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

In large rivers, some species can develop mass occurrences that form huge swarms when millions of individuals slip in synchronized fashion. These have already been mistaken for the clouds of smoke from a major fire on satellite or radar images.

The caddis fly larvae generally live on particulate organic matter. They either scrape off the organic coating of algae etc. ( biofilm ) on the surface of stones, or they feed on decomposed fallen leaves and other plant debris; very rarely also from dead wood. Some families have specialized as filter feeders (e.g. Hydropsychidae, Polycentropodidae). They build drift nets made of their self-made webs across the flow, the nets can be funnel-shaped or irregular in shape. There are also a number of predatory species (e.g. many species in the Rhyacophilidae family).

Many caddis fly larvae are indicators of saprobial water quality; most species only occur in bodies of water with good to very good water quality. However, other species regularly occur up to the critically contaminated area (quality class II-III). A number of other species live exclusively or preferentially in stagnant water (e.g. Phryganeidae).

Systematics of caddis flies

The caddis flies are divided into two sub-orders on the basis of the number of limbs of the jaws: the Aequipalpia or Annulipalpia have five-limbed palps, the Inaequipalpia or Integripalpia have two to four-limbed palps. Different taxonomists distinguish a third suborder Spicipalpia with four families, it corresponds to the superfamily Rhyacophiloidea in the overview. While the demarcation of the other subordinate orders appears relatively clear, there is great disagreement about the position of these four families in the family tree.

The following list contains the families in which European species can be found (the species numbers refer to Europe):

Fossil evidence

Caddis fly in Baltic amber

The oldest fossil evidence of caddis flies comes from the Lower Permian . In addition, representatives of this family are not uncommon in Cretaceous and Tertiary amber worldwide . In Baltic amber , caddis flies with more than 150 specific species make up around 5% of the total fossil fauna. A total of about 650 fossil caddisflies have been described. Since a few caddis flies have similarly scaled wings as butterflies , the two orders Lepidoptera and Trichoptera are assigned to the common ancestor Amphiesmenoptera .

swell

  1. ↑ Ralph W. Holzenthal, Roger J. Blahnik, Aysha L. Prather, Karl M. Kjer: Order Trichoptera Kirby, 1813 (Insecta), Caddisflies. In: Zootaxa. Volume 1668, 2007, pp. 639-698.
  2. ↑ freshwaterecology.info
  3. ↑ John Huxley, Peter C. Barnard: Wing ‐ scales of Pseudoleptocerus chirindensis Kimmins (Trichoptera: Leptoceridae) . In: Zoological journal of the Linnean Society . 92, No. 3, March 15, 1988, pp. 285-312. doi : 10.1111 / j.1096-3642.1988.tb01514.x . Retrieved March 15, 2013.
  4. ^ Quiver of Crunoecia irrorata on eol.org
  5. ↑ Thremma gallicum McLachlan, 1880: On the biology, ecology and distribution of faunal specificity Germany. (PDF; 670 kB) In: Entomology Today. Volume 17, 2005, pp. 13-26.
  6. ^ Caryn C. Vaughn: Evolutionary ecology of case architecture in the snailcase caddisfly, Helicopsyche borealis. In: Freshwater Invertebrate Biology. Volume 4, No. 4, 1985, pp. 178-186.
  7. ^ Robert Hinchliffe, AR Palmer: Curious chiral cases of caddisfly larvae: handed behavior, asymmetric forms, evolutionary history. In: Integrative and Comparative Biology. Volume 50, No. 4, 2010, pp. 606-618. doi : 10.1093 / icb / icq069 .
  8. ^ W. Mey: The terrestrial larvae of the genus Enoicyla Rambur in Central Europe and their distribution (Trichoptera). In: German Entomological Journal. Volume 30, 1983, pp. 115-122.
  9. ^ FM Carpenter, L. Burnham: The geological record of insects . In: Ann. Rev. Earth Planet. Sci. Volume 13, pp. 297-314, cited in Poinar 1992.
  10. ↑ George O. Poinar, Jr .: Life in Amber. Stanford University Press, Stanford (Cal.) 1992, ISBN 0-8047-2001-0 .
  11. ↑ Wolfgang Weitschat, Wilfried Wichard: Atlas of plants and animals in the Baltic amber. Pfeil-Verlag, Munich 1998, ISBN 3-931516-45-8 .
  12. ^ Paul Whalley: A review of the current fossil evidence of Lepidoptera in the Mesozoic . In: Biological Journal of the Linnean Society . 28, No. 3, June 28, 2008, pp. 253-271. doi : 10.1111 / j.1095-8312.1986.tb01756.x . Retrieved March 15, 2013.

literature

  • State Institute for the Environment Baden-Württemberg (2000): Caddisflies: Building artists and bio-indicators of our waters. LUBW worksheets 25.
  • Bernhard Klausnitzer: Trichoptera, caddis flies. In: Westheide, Rieger (Ed.): Special Zoology Part 1: Protozoa and invertebrates. Gustav Fischer Verlag, Stuttgart / Jena 1997, pp. 670-671.
  • W. Mey: Trichoptera - caddis flies. In: HJ Hannemann, B. Klausnitzer, K. Senglaub: Exkursionsfauna von Deutschland Volume 2: Invertebrates: Insects. Spektrum Akademischer Verlag, Berlin 2000, ISBN 3-8274-0922-5 , pp. 553-570.
  • W. Wichard: The caddis flies. Neue Brehm Bücherei 512, 1988, ISBN 3-89432-323-X .

Web links

Commons : Trichoptera  - album with pictures, videos and audio files