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Updated: October 09, 2013
The wings of Trichoptera are covered with setae, from which the name of the order is derived (from the Greek "trichos"= hair, and "pteron"=wing).
Three superfamilies have been distinguished, which include five groups based on case-building behaviour. Hydropsychoidea (Hydropsychidae, Philopotamidae, Polycentropodidae, and Psychomyiidae) are the net spinners and retreat makers; Rhyacophiloidea include the free-living forms (Rhyacophilidae), saddle-case makers (Glossosomatidae), and purse-case makers (Hydroptilidae); and Limnephiloidea are the tube-case makers.
Mass emergences of some species from large rivers are considered a nuisance by residents, since the insects are attracted to outdoor lights; human allergies to the scales on their wings have also been reported. The larvae of some leptocerids are reported to damage the young shoots of rice plants in paddy fields. The larvae of a few species are known to eat fish eggs. On the beneficial side, many hydropsychids prey on black fly larvae.
Many species that inhabit temporary ponds lay eggs in the basins of dry pools in the fall, when the soil surface is beginning to become more moist. After larvae hatch, they may remain within the gelatinous matrix for months until the pool basin is reflooded. Moisture is the apparent stimulus for larvae to break out of the gelatinous matrix and begin case building or net spinning.
Adult caddisflies differ from moths in a number of aspects foremost amongst which are patterns of wing venation and structure of the mouthparts. Adult caddisflies are small (1.5 mm body length) to moderate-sized (4.0 cm), tend to be drab in colour, and are mostly active at night, especially around lights. During the day they hide in riparian vegetation. The compound eyes are well developed and there may be up to three ocelli. The mouthparts are weak and are capable only of ingesting liquids. All three thoracic segments are distinct. The legs are long and slender.
Caddisfly larvae are quite similar to lepidopteran caterpillars but have only a single pair of abdominal prolegs which are located on the terminal segment and are each equipped with an apical anal claw. The larval thorax is well developed, with at least the pronotum covered dorsally by a pair of sclerotized plates.
The trichopteran pupa is exarate and, in case-building species, develops within the larval case after it has been secured to the substrate and sealed with silk. In free-living species, the final instar larva builds a special pupal case, generally made from silk and mineral particles, again this is firmly attached to the substrate. In most species, the pupa is equipped with heavily sclerotized mandibles which enable it to cut an opening in the case so that it may escape and swim to the water surface.
At present, caddisflies inhabit a wide range of habitats from the ancestral cool streams to warm streams, permanent lakes and marshes, and permanent and temporary ponds. One species has been found in tide pools off the coast of New Zealand; the females oviposit through the papillar pores of starfishes. Caddisflies have been generally classified as clingers, sprawlers, or climbers, although a few are burrowers.
Although caddisfly larvae are found in a wide range of aquatic habitats, the greatest diversity occurs in cool running waters. Furthermore, in families represented in both lotic and lentic habitats, the genera exhibiting more ancestral characters tend to be found in cool streams whereas those showing more derived characters tend to occur in warm, lentic waters. These two findings point to cool, running waters as the most likely primordial caddisfly habitat, the one in which the ancestors of the Trichoptera first became aquatic and the one in which differentiation into the basic groups (superfamilies) took place (Williams & Feltmate, 1994).
|Family||Distribution and Habitat|
|Rhyacophilidae||All major zoogeographical zones except Australian, Neotropical, Afrotropical & the Antarctica; in cool running waters|
|Hydrobiosidae||Mainly confined to Australian & Neotropical regions; running waters|
|Glossosomatidae||Cosmopolitan; running waters|
|Hydroptilidae||Cosmopolitan; running & standing waters|
|Hydropsychoidea (Net-spinning caddisflies)|
|Philopotamidae||Cosmopolitan; running waters|
|Stenopsychidae||Oriental, Australian, Afrotrop. & Asian Palaearctic regions; fast-flowing rivers|
|Hydropsychidae||Cosmopolitan; running waters & wave-swept shores of lakes|
|Polycentropodidae||Cosmopolitan; running & standing waters|
|Dipseudopsidae||Afrotropical & Oriental regions (1 genus in the Nearctic); lakes & slow-flowing waters|
|Ecnomidae||All regions except the Nearctic; lakes, ponds & slow-flowing waters|
|Psychomyiidae||All regions except Australian & Neotropical; cool running waters, some in lakes|
|Xiphocentronidae||Afrotropical, Oriental, Neotropical & extreme south of Nearctic (Mexico, Texas); small streams|
|Limnephiloidea (Tube-case-building caddisflies)|
|Phryganeidae||Confined to Nearctic, Palaearctic & Oriental regions; mainly lakes & marshes, slow-flowing streams, temporary pools|
|Phryganopsychidae||Himalayas & China to Japan, Korea & adjacent Siberia|
|Brachycentridae||Confined to Nearctic, Palaearctic & Oriental regions; running waters (cool streams to large rivers, depending on genus)|
|Limnocentropodidae||Oriental Region & Japan; rapid streams|
|Chathamiidae||Restricted to Australian Region; embryogenesis takes place in coelom of starfishes, larvae become free living in coastal waters (marine)|
|Tasimiidae||Australian & Neotropical regions only; clear mountain streams|
|Limnephilidae||Mostly in cooler parts of Nearctic & Palaearctic, some in adjacent Oriental, some in temperate Neotropics (Dicosmoecinae), a few in Australian & Afrotropic regions; most types of running & standing waters, including temporary & brackish waters|
|Goeridae||All regions except Australian & Neotropical; running waters, especially spring seeps|
|Thremmatidae||Confined to southern Europe; cold mountain streams|
|Uenoidae||Western North America, Japan & Himalayas; rapid streams|
|Lepidostomatidae||All regions except Australian, but in Neotropical only in montane Central America, not South America; mainly slow, cool running waters; littoral of lakes|
|Oeconesidae||Confined to Australian Region; forested streams, in plant debris|
|Kokiriidae||Confined to Australian & Neotropical regions; sandy substrates in streams & lakes|
|Plectrotarsidae||Confined to Australia; larvae unknown|
|Beraeidae||Eastern Nearctic & European Palaearctic; cool streams, springs & organic muck in spring seeps|
|Sericostomatidae||All regions except Australian; flowing & standing waters|
|Conoesucidae||Confined to Australian Region; streams|
|Antipodoeciidae||Confined to Australia, larvae unknown|
|Calocidae||Confined to Australia & New Zealand; small forested streams|
|Helicophidae||Confined to Australia & N.Z.; clear, fast streams|
|Molannidae||In Holarctic & Oriental regions; sandy substrates in standing or slow-flowing waters|
|Odontoceridae||All regions, except Afrotropic; running waters|
|Atriplectididae||Known from Australia & Seychelles; bottom sediments in lakes & slow rivers|
|Philorheithridae||Confined to Australian & Neotropical regions; cool, rocky streams|
|Helicopsychidae||Cosmopolitan, but with greater diversity in tropics; cool & warm running waters; littoral zone of lakes|
|Calamoceratidae||All regions (but sparse), but mainly subtropical; slow streams, coastal lakes, swamps; phytotelmata|
|Leptoceridae||All regions (abundant); mainly standing waters; slower sections of rivers|
A final point worth mentioning about the Trichoptera, in general, and about those that live in small streams in particular, concerns habitat specificity. Many species that are restricted to small streams reflect the ecological characteristics of the surrounding terrestrial community. In such streams, conditions for the larvae are affected by shade in summer or winter, the amount and periodicity of leaf-fall, and the distribution of local precipitation, all three of which are integrated with the type of climax community occupying the general area. As a result, there is, in general, a marked correlation between these terrestrial biomes and the ecological affinities of their respective small-stream caddisfly faunas. Such correlations are of enormous importance to palaeoecology, and caddisfly remains are proving to be a powerful tool in the interpretation and reconstruction of past environments (Williams & Feltmate, 1994).
|Species||General habitat||Feeding||pH||Oxygen %||Trophic|
|Agapetus spp.||turtle case, streams||scraper||≥7||≅100||Oligo|
|Agraylea spp.||silk purse, streams, lakes||piercer, gatherer||≤7 - >7||≅100||upper Meso|
|Banksiola spp.||tapered cylinder of leaves in spiral; slow streams, lakes||shredder, piercer (last 2 instars)||<7 - >7||>50||upper Meso|
|Brachycentrus americanus||tapered square tube of plant material; on logs & plants in streams||filter feeder, scraper||≥7||>50||upper Meso|
|Cheumatopsyche spp.||silk net, warmer streams||filter feeder||<6 - >7||25 - 100||lower Meso|
|Chimarra spp.||sac-like nets, warmer streams||filter feeder||≥7||≥50||Meso|
|Frenesia spp.||tube of mineral, wood; cool springs||shredder||>7||approx. 100||Oligo|
|Glossosoma nigrior||turtle case, streams||scraper||≥7||approx. 100||Oligo|
|Helicopsyche borealis||spiral case, streams||scraper||<7 - >7||>50||upper Meso|
|Hydropsyche spp.||silk net, streams||filter feeder||≥7||>50||upper Meso|
|Hydroptila spp.||silk purse, streams||piercer, scraper||≤7 - >7||approx. 100||Oligo|
|Lepidostoma spp.||tapered tube of sand, headwater streams||shredder||≅7||>50||upper Meso|
|Leptocerus americanus||silk tube, lakes||shredder||<7 - >7||>50||upper Meso|
|Limnephilus spp.||case variable, omnipresent, lakes, streams||omnivorous||≤7 - >7||25 - 100||None|
|Molanna blenda||tube case with lateral flanges, lakes, streams||shredder, gatherer, piercer||≤7||>50||lower Oligo|
|Mystacides sepulchralis||tube of sand, plant material, streams, lakes||gatherer, shredder||≤7 - >7||approx. 100||Oligo|
|Neophylax spp.||tapered tube of sand, streams||scraper||>7||approx. 100||Oligo|
|Neureclipsis crespuscularis||trumpet-like net, streams||filter feeder, shredder, piercer||≤7 - >7||approx. 100||Oligo|
|Oecetis spp.||tapered, curved tube, streams, lakes||piercer||≤7 - >7||>50||lower Oligo|
|Phryganea cinerea||tapered cylinder of leaves in spiral, streams, lakes||shredder, piercer||≤7 - >7||>50||lower Meso|
|Phylocentropus placidus||silk tube, headwater streams||filter feeder||approx. 7||approx. 100||Oligo|
|Polycentropus cinereus||silk tube, streams||piercer, filter feeder, shredder||5 - >7||>50||upper Meso|
|Psychomyia flavida||sac-like nets, streams||gatherer, scraper||<7 - >7||approx. 100||Oligo|
|Rhyacophila spp.||free-living, streams||piercer, gatherer, shredder||<7 - >7||approx. 100||Oligo|
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