In no small way, aquatic insects help to sustain streams, rivers, marshes, and lakes as functional, productive ecosystems; and caddisflies are major components of all of these communities. Caddisflies, or Trichoptera,* are a relatively small order of insects widely distributed on almost every habitable land mass. Between 9000 and 10,000 species are now known in the world, but the rate at which species new to science continue to be discovered indicates that the actual world fauna is very much larger (Malicky 1973, 1993; Schmid 1984). These insects have made little impact on popular attention, probably because most adult caddisflies are...

Three suborders and six superfamilies are recognized here in the Trichoptera, in accordance with phylogenetic evidence and proposals outlined at length by Frania and Wiggins (in press). A higher classification of three superfamilies – Rhyacophiloidea, Hydropsychoidea, and Limnephiloidea – was employed by Ross (1956, 1967) and is widely used elsewhere, including the first edition of this book. The three suborders employed here – Spicipalpia, Annulipalpia, and Integripalpia – are equivalent to the three superfamilies of Ross (1956), but are based on independent phylogenetic analysis of much new evidence (Frania and Wiggins, inpress). The superfamilies used here are in accordance with the groups of Frania...

All three subordinal groups of Trichoptera are represented in cool, running waters (Fig. I). In families represented in both lotie and lentic waters, the genera with more primitive morphological character states occur in cool, lotic habitats, and those with derived states occur in wanner lentic sites (Ross 1956).

The closed cocoons of spicipalpian families represent ancestral construction behaviour shared with primitive Lepidoptera (Wiggins and Wichard 1989). From the preponderance of Spicipalpia in running waters, it is inferred that these families are physiologically constrained to cool, lotic waters, where respiration of the pupae is sustained solely by the diffusion of oxygen...

Morphological terms of a general nature can be found in an entomological text or glossary. Those that have particular application to the Trichoptera are explained here and illustrated in Figures III–VI. Morphological structures of larvae in many of the same genera occurring in Russia were illustrated by Lepneva (1964, 1966).

A distinction between spines and setae should be made at the outset.Spinesare extensions or processes of the cuticle; they may be short and pointed, longer and blade-like, comb-shaped, or of some other form. Spines are one type of surface sculpturing, and as an integral part of the...

To a considerable degree, the objective in collecting will govern the method and the equipment used. The topic is first considered here from the viewpoint of discovering as far as possible the full diversity of caddisfly larvae in a given site. Other objectives are considered subsequently.

Equipment for collecting caddisfly larvae need not be elaborate. For waters that can be waded, thigh-length rubber boots are useful; the main advantage is to have freedom to kneel down for a close look at the insects and what they are doing. A strainer of the finest mesh possible is useful for washing silt...

1 Larva with portable case of sand grains resembling snail shell (Fig. 17.1c); anal claw with comb of teeth, not hook-shaped (Fig. 17.ID) Widespread

17 Helieopsychidae, p. 237

Larva with case not resembling snail shell, or larva not constructing portable case; anal claw with apex forming stout hook (Fig. VA–D) 2

2 (1) Dorsum of all three thoracic segments largely covered by sclerotized plates (Figs. 3.10A, 7.5A) 3

Metanotum, and sometimes mesonotum, entirely membranous or largely so but with several pairs of smaller selerites (Figs. 8.1B, 20.1B) 5

3 (2) Abdomen with ventrolateral rows of branched gills, and with...

Larvae construct a closed, osmotically semipermeable, cocoon of silk for pupation; since the water current cannot reach the pupa directly, respiration during metamorphosis is effected solely by diffusion of oxygen across the wall of the closed cocoon. All construction by larvae is for pupation, or derived from pupation behaviour with the time of onset altered.

Larvae differ in foraging and pupation behaviour within this group. In the Rhyacophilidae and Hydrobiosidae, larvae are mainly predacious and free-living without portable cases. Larvae in the Glossosomatidae construct a precocious pupal shelter at the beginning of the first instar, and utilize it as a...

Glossosomatids live chiefly in rivers and streams, where they are common and often abundant. A European species,Agapetus fuscipesCurtis, is reported from lakes (Mackereth 1956), andGlossosomalarvae have been collected along the rocky, wave-washed shore of Lake Superior. The family is represented in all faunal regions; six genera are recognized in North America, where approximately 80 species are known in the United States and Canada.

Larvae of this family are specialized for feeding on the uppermost exposed surfaces of rocks, where they graze on diatoms, green algae, and fine organic particles (e.g. Anderson and Bourne 1974). Scraper mandibles...

The Hydrobiosidae are widely distributed in South America, Australia, and New Zealand; the family extends through the Pacific island network of New Guinea and Indonesia to eastern Asia. In the New World, the genusAtopsycheis widespread in Central America and reaches the southwestern United States.

Larvae of this family are similar to the Rhyacophilidae in structure and behaviour, and appear to fill the same free-living predator niche in the southern hemisphere that Rhyacophilidae do in the northern hemisphere. Interestingly, neither family occurs in southern Africa.

The larvae are campodeiform, with a prognathous head. As in the Rhyacophilidae, only the...

Often called micro-caddisflies because they include the smallest Trichoptera of 2 to 3mm in length, the Hydroptilidae also include genera in which the larvae reach 6 mm and differ little in size from some of the Glossosomatidae and Psychomyiidae. Hydroptilids occur in all faunal regions, and although richly represented in tropical latitudes where they account for a large part of the caddisfly fauna, they are still an abundant and highly diverse group through much of North America. Sixteen Nearctic genera with about 220 species are recognized north of Mexico, and there can be little doubt that many more species are...

The Rhyacophilidae are a large and important family in cool, running waters o f the Hol-arctic and Oriental regions. Two genera are recognized in North America:HimalopsycheandRhyacophila.

Rhyacophilid larvae are free-living, passing their entire larval existence without constructing either a portable case or a fixed retreat. Larvae crawl actively over rocks, and are reputed to leave a silken thread wherever they go (Ross 1956). Just before pupation, the larva fashions a crude enclosure of small stones, either dome-shaped on a rock surface or ring-like between two rocks; within this enclosure it spins a closed cocoon of tough silk...

Larvae are campodeiform with a prognathous head; the anal prolegs are elongate and the claws are prominent. They forage mainly from a stationary position, collecting food transported by water through filtering or grazing on deposits of fine organic particles; they also graze on diatoms. Larvae construct a fixed tubular retreat at the beginning of the first instar, supplemented in some families by a capture net of silken threads. For pupation, most larvae construct a protective dome of rock fragments at the end of the last larval instar; the inner cocoon is osmotically permeable, and in most families, water currents enter...

Larvae of this family are among the most unusual in the Trichoptera. The fixed silken tube covered with sand grains, characteristic of several other families in the Annulipalpia, is used in the Dipseudopsidae to collect food materials suspended in the current. By adopting the behaviour of burrowing in soft sediments and extending the openings of their tubes above the substrate, larvae ofPhylocentropusare able to divert a portion of the current through the buried tube system and remove suspended food particles in a filter of silken mesh. They have, in effect, duplicated the filter-feeding behaviour of other Annulipalpia, such...

The family Ecnomidae is represented in most faunal regions of the world; in North America only the genusAustrotinodesfrom southern Texas is known. Species ofAustrotinodesoccur through Mexico and Central America, and also in Chile (Flint 1973); the genus is closely related toEcnominaof Australia and New Zealand. Presumably, the Ecnomidae reached North America by way of Gondwanian continents of the southern hemisphere, and not from Eurasia where the genusEcnomusoccurs.

Larvae of the Ecnomidae share characters with the Polycentropodidae and Psychomyiidae, and were for some time treated as a subfamily of the latter group; their...

The Hydropsychidae are a large and dominant family of caddisflies living in running waters over much of the world; a few species occur along wave-washed shorelines of lakes. Ten genera are known in the Nearctic region, and usually several of them are represented in a single stream system, their larvae distributed over the longitudinal range of lotic habitats according to differing requirements of temperature, current speed, and oxygen saturation (e.g. Wiggins and Mackay 1978). Hydropsychid caddisflies are extremely important in the ecology of running-water systems because of their ubiquitous occurrence, abundance, and large biomass. Approximately 145 species are recorded in...

The Philopotamidae occur in running waters in all faunal regions of the world; the three Nearctic genera are common and widespread over much of the continent, with approximately 40 species known north of Mexico. Larvae spin elongate, sack-like nets of silken mesh to filter fine particulate organic matter from currents, and among all the filter-feeding Trichoptera, philopotamids utilize the finest particles.

Larvae usually live on the undersides of rocks, their nets collapsing as amorphous silt-covered masses when the rock is removed from water. The nets are fastened by the anterior edge to the rock in such a way that they...

The Polycentropodidae are an important group of retreat-making Trichoptera in all major faunal regions. The family is widespread over much of North America, where there are six genera with nearly 70 species known north of Mexico.

In general structure this family shows some similarity to the Psychomyiidae, and in fact the Polycentropodidae have been treated as a subfamily of the Psychomyiidae in some North American works (e.g. Ross 1959; Flint 1964a). The Polycentropodidae are most readily distinguished by the pointed fore trochantin, fused without a separating suture to the episternum (Figs. 9.2A, 9.3A). In polycentropodid larvae the tip of the...

The Psychomyiidae are a small family widely distributed over much of the world. Four genera are recognized in the Nearctic region, with a total of about 17 species in Canada and the United States; representatives occur in most parts of the continent, at least one ranging as far north as the tree line.

The larvae differ from those of the Polycentropodidae in several features. One character diagnostic for the Psychomyiidae is the broad, hatchet-shaped trochantin of the prothorax, which is separated from the propleuron by a well-marked suture (Fig. 10.4C). The labium is extended well beyond the anterior margin of...

From inception as a family of one genus (Ross 1949), the Xiphocentronidae have become through recent revision a family of seven genera with about one hundred species (Schmid 1982). As defined by Schmid, the family is widely distributed through Asia, Africa, South America, Central America and the Antilles, and North America. The genusXiphocentronis represented in southwestern North America. Adults of a second genus of this family,Cnodocentron, have been recorded from Arizona (Mou1ton et al. 1994); larvae are unknown inCnodocentron.

Larval diagnosis for the entire family cannot be given because four of the seven genera assigned to...

Larvae are mostly eruciform with an hypognathous head; the anal prolegs are short and the anal claws are small. Portable cases constructed in all instars enable larvae to move to new food resources. Pupation in most families occurs within the larval case, after the case has been fixed to a substrate and the ends closed against predators. Small openings in the ends of the case permit water to flow directly over the developing pupa for respiration; a flow of water through the case is regulated by the ventilating undulations of the insect’s abdomen.

The world fauna of the Integripalpia consists...

The family Apataniidae (Gall and Wiggins, in press) brings together the subfamily Apataniinae, formerly of the Limnephilidae, with four of the genera placed previously as Lim-nephilidaeincertae sedis(Wiggins 1973c). Members of the Apataniidae are widespread in the Holarctic and Oriental faunal regions; five genera are represented in North America.

The Apataniidae represent the coincidence of several uncommon trends in larval characters: wedge-like shape of the ventral apotome; mandibles with scraper blades for grazing; pronotum inflated; and metanotalsa1 with many setae on the integument. Not all of these characters occur in each genus, and the genera differ in some...

The Beraeidae are a small family sparsely distributed over the Holarctic region. Only the single genusBeraeaoccurs in North America, and it is confined to the eastern part of the continent, where colonies are exceedingly local. Larvae of the Holarctic genera differ somewhat structurally (Wiberg-Larsen 1979), but apparently are consistent in marked reduction of the lateral sclerite of the anal proleg (Fig. 13.1A, D), which is usually extended posteriorly as a lobe bearing a single stout seta; the mesal surface of the base of the anal claw is membranous and bulbous, and bears a characteristic prominent brush of the...

This family is widespread over the Holarctic and Oriental regions. All five genera now recognized in the Brachycentridae occur in North America, and three are endemic. Representatives of the Brachycentridae occur in most parts of the continent, and approximately 30 species are known.

Brachycentrids live in running waters, ranging from cold mountain springs to the slowly flowing channels of marshy rivers. In small streams larvae are usually concealed in moss, but in larger rivers the larvae fix their cases to exposed substrates in the current. Species of these larger rivers are often locally abundant.

Larvae of this family are unique...

This is a family of essentially tropical and subtropical distribution through all faunal regions; northward extensions into North America have given rise to three genera with five species in eastern and western parts of the continent.

The North American species occur in streams where detritus accumulates in pools and areas of slower current. Larvae of at least one South American species live in water held in the leaf bases of bromeliads. Evidence for some species indicates that plant detritus is the major food of the larvae, although as in many detritivores it may be largely the associated microorganisms that are...

This is a family of about 10 genera and 100 species, represented in all faunal regions of the world except the Neotropical and Australian. As now defined (Gall and Wiggins, in prep.), the Goeridae comprise four genera in North America, where three of them are endemic.

Larvae live in running waters, ranging from small cold springs to rivers. For the most part, larvae graze algae and fine organic particles from exposed rock surfaces and have typical scraper mandibles; but larvae ofLepaniaare confined to water-saturated organic muck of spring seepage, and have toothed mandibles.

Larvae of the Goeridae are...

So abundant and widespread are these caddisflies, it is easy to forget that the larvae are among the most remarkable of all insects. Their helical cases of closely fitted rock fragments are an outstanding example of the elegance and precision of insect behaviour. The family comprises four genera, with representatives widely distributed over most faunal regions (Schmid 1993); a single genus,Helicopsyche, occurs in North America. Aspects of the morphology and biology of a European species were outlined by Botoşǎneanu (1956).

Larval cases of most species resemble tightly coiled snail shells, although a Cuban species has an open-coiled case (Botoşǎneanu...

The Lepidostomatidae are widely distributed over much of the world, primarily in the Holarctic, Oriental, and Afrotropical regions; a few species also occur in northern parts of the Neotropical region of Mexico through Panama, and of the Australian region in New Guinea. A synopsis of the North American Lepidostomatidae has been provided by Weaver (1988) in which about 80 species are recognized.

Genera have been unstable through much of the taxonomic history of the Lepidostomatidae. Generic characters based on the richly varied secondary sexual structures of the males led to the proposal of some 15 names in North America; these...

The Leptoceridae are a large and flourishing family represented in most of the world’s faunal regions. Approximately 100 species are known in Canada and the United States in eight genera; they are common and widespread as a group and often abundant locally.

Almost all Nearctic leptocerid larvae can be distinguished by their long antennae; the exceptions are some sponge-feeding species ofCeracleain which the antennae have probably become secondarily shortened. Leptocerid larvae are further distinguished by additional unpigmented lines of weakness where primary sclerites of the head and thorax usually subdivide at ecdysis. All of the Nearctic larvae of...

The Limnephilidae are the largest family of Trichoptera in North America, with some 230 species now assigned to 39 genera. The group is dominant at higher latitudes and elevations through much of the northern hemisphere.

Larvae of Limnephilidae occupy a wider range of habitats than any other family in the Trichoptera, reflected in the fact that about one-quarter of all Nearctic caddisfly genera are members of this single family. There are genera characteristic of spring streams, of rivers, of lakes, and of marshes; there are some whose larvae live in temporary pools and streams, and a few limnephilid larvae in...

This is a small but distinctive family of the Holarctic and Oriental faunal regions. Two genera are represented in the Nearctic fauna, with only seven species.

Molannid larvae can be recognized immediately in the field by their flattened cases of small rock fragments, which have lateral flanges and a hood over the anterior opening. Since the cases blend with the surrounding sand substrate and no part of the insect is visible from above, larvae are usually detected only when they move their case. Similar flanged cases are made by some species in the leptocerid genusCeraclea, but they are stout,...

This is a small family represented in most faunal regions. Thirteen species are known north of Mexico representing six genera, three of which are monotypic; apart from somePsilotreta,the North American species tend to be local and obscure. These can be interpreted as characteristics of a senescent group, once widespread but with the passing of time increasingly confined in habitat and distribution.

Morphologically, there is such marked diversity among larvae of the North American genera that it is difficult to find congruent diagnostic characters at the family level. The mesonotal plates are heavily sclerotized, separated in most genera only...

The Phryganeidae are a family of the Holarctic and Oriental regions, numbering about 75 species in 15 genera. For the most part, they are insects of northerly latitudes or high elevations; in North America there are 10 genera with 28 species. Larvae of different genera live in a wide range of aquatic habitats: spring streams, marshes, lakes to depths of 100 m, and temporary vernal pools. Available evidence suggests that overall the larvae are omnivorous, although some are largely predacious for at least part of their life cycle.

Larvae are large, often over 40 mm long, but morphologically homogeneous. Intersegmental...

This family of two western North American genera was recognized in an extensive phylogenetic analysis of the Limnephiloidea (Gall and Wiggins, in press). It is supported by derived character states of larvae, pupae, and adults; these states are not congruent with any of the related families.

Larvae of the Rossianidae are distinctive from a ll other case-making families. The head and pronotum bear coarse surface sculpturing; the mesepisternum is modified by prominent surface sculpturing. Primary sclerotized plates of the mesonotum are subdivided into two or three pairs of secondary sclerites. Setae of the metanotum are confined mainly to three pairs...

The Sericostomatidae sens. str. are represented in all faunal regions except the Australian, usually by a small number of genera and species. The twelve North American species have been assigned to three genera (Ross and Wallace 1974). Representatives are widespread through the eastern half of the continent and in the west.

Larvae are generally found in running waters, often in small springs, but also in the littoral zone of lakes. Observations indicate that larvae of at least the two eastern genera,AgarodesandFattigia,are burrowers in sandy deposits; evidently those of the westernGumagado not burrow to the...

This is a distinctive family of North America, eastern Asia including Japan and the northeastern Himalayas, and southern Europe; about 70 species are now known in the world.

At the family level larvae are distinguished by the anteromedian emargination of the mesonotum. They are also characterized by a wedge- or T-shaped ventral apotome of the head, a prosternai horn, and a membranous border on the labrum; antennae arise midway between the eye and the anterior margin of the head capsule. The basal seta of each tarsal claw extends nearly to the tip of the claw. Single abdominal gills are present...