encyclopedia of inland waters || trichoptera (caddisflies)

Trichoptera (Caddisflies)R W Holzenthal, University of Minnesota, MN, USA

ã 2009 Elsevier Inc. All rights reserved.

Introduction

Trichoptera, or caddisflies, with over 13 000 speciesdescribed from all faunal regions, is the seventh larg-est insect order and the largest order of primaryaquatic insects (Figure 1(a)–(c)). There are about1000 more caddisfly species than the other primaryaquatic orders combined (dragonflies, mayflies, stone-flies, dobsonflies). The order is divided into 45 familieswith just over 600 genera. The recent elevation ofPtilocolepidae to a 46th family from its former statusas a subfamily in Hydroptilidae is controversial. Alist of all known species is available online from theTrichoptera World Checklist.The known species diversity probably represents

far less than the actual diversity, which has beenestimated as high as 50 000 species. Recent biodiver-sity inventories in tropical regions around the world,for example, the northern Andes and southeasternBrazil in South America, Ghana in West Africa, andThailand and Indonesia in Southeast Asia, haveyielded faunas of hundreds of new species. NorthAmerica and Europe have well-known faunas, butlarge parts of temperate Asia, particularly China,have only recently been explored and are revealing avery diverse caddisfly fauna. Southern TemperateZones, including southern Africa, Australia, NewZealand, and southern South America, have diverseand highly endemic faunas, including families en-demic to these regions.

Morphology

Adults

Adult Trichoptera are terrestrial and look much likedrab, fragile moths, often occurring in large numbersin lakeside or streamside habitats. Trichoptera areclosely related to the order Lepidoptera and togetherthe two orders comprise Superorder Amphiesmenop-tera, or ‘dressed-up wings,’ in reference to the denseclothing of scales or hairs on the wings. In Trichop-tera, both pairs of wings and the body are coveredwith hairs, or occasionally with patches of scales.Caddisfly adults are usually inconspicuously coloredin shades of brown or gray, probably an adaptationallowing them to hide during the day in riparian vege-tation (Figure 2(a) and 2(b)). A number of species,however, are brightly colored with yellow, orange,green, silver, blue, or sometimes iridescent-colored

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hairs and scales on the wings and thorax (Figure 3(a)and 3(b)). In either case, the distinct patterns of differ-ently colored hairs on the wings frequently allow rec-ognition of the species, much as in their often morecolorful lepidopteran cousins. Adult body lengthranges from a few millimeters in the smallest Hydro-ptilidae and some Glossosomatidae to about 4.5 cmin the largest Phryganeidae.

Adults are easily recognized by a number of addi-tional features. The mouthparts are reduced, withthe mandibles absent or highly vestigial and non-functional, but the maxillary and labial palps areprominent (Figure 4(a)). The major feature of thetrichopteran mouthparts is the haustellum, a uniquestructure for the order, composed of the fused labium(the prelabium) and the hypopharynx to form a shortproboscis used to soak up water or sugary liquids.The compound eyes are well developed, and simpleeyes, or ocelli, are present in several families. A com-plete complement of wing veins is found in themore primitive families and genera, with loss andfusion of veins occurring commonly throughout theorder (Figure 5(a) and 5(b)). Wings are generally heldroof-like or tent-like when folded over the body, butin some groups they are held flat. In most species, theantennae are filamentous and about as long as thebody, but in some families they can be several timeslonger than the body. Legs are long and slender. Dor-sally the head and thorax bear characteristic setalwarts comprised of clearly delineated, slightly con-vex, setose regions of the cuticle. The male genitalia,associated with abdominal segments 9 and 10, areconspicuous, complex, and contain the primary char-acters for delineating genera and identifying thespecies. Females lack a true ovipositor, but insteadhave the terminal abdominal segments (segments9–10 or 11) either elongated into a protrusible ‘ovis-capt’ for placing eggs on the substrate or modifiedinto a shorter apparatus for forming and holding theegg mass.

Larvae

Larvae are aquatic and construct a portable case orfixed retreat, except for a couple of ‘free-living’families. The head capsule is well developed and fullysclerotized. The antennae are very short and consistof a single segment, although in the long-horned cad-disflies (Leptoceridae) and in some microcaddisflies

Figure 1 Life history stages of Trichoptera. (a) Larva of acase-making caddisfly, family Limnephilidae; (b) pupa of

a case-making caddisfly, family Leptoceridae; (c) adult of a

case-making caddisfly, family Limnephilidae.

Figure 2 Adult Trichoptera. (a) Hydrobiosidae, genusAtopsyche; (b) Xiphocentronidae, genus Xiphocentron.

Figure 3 Adult Trichopera. (a) Calamoceratidae, genus

Phylloicus; (b) Leptoceridae, genus Nectopsyche.

Figure 4 Head morphology of adult and pupal Trichoptera.

(a) Head of a phryganeid adult, lateral view, showing the

well-developed haustellum; (b) head of a leptocerid pupa,

frontal view, showing the well-developed mandibles.

Invertebrates _ Trichoptera (Caddisflies) 457

(Hydroptilidae), the antennae are long and conspicu-ous. Larval eyes are always present and consist of afew facets. Like most holometabolous larvae, theyhave chewing mouthparts consisting of a smalllabrum, a pair of well-developed mandibles, short,

compact maxillae, and a labium. Short maxillaryand labial palps are usually present. The opening ofthe silk gland is at the apex of the labium. Mandiblesof shredders and herbivores are broad, with apicalcutting teeth, whereas those of scrapers are moreelongate with entire edges. In predaceous larvae,such as in the genus Oecetis, the apical teeth are

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Figure 5 Wings of Trichoptera. (a) Forewing; (b) Hind wing.

458 Invertebrates _ Trichoptera (Caddisflies)

more pointed. The thoracic segments are distinct andeach bears a pair of legs. These are either more or lessthe same length or the foreleg is the shortest and thehind leg is the longest. Legs are unmodified in mostspecies, but in some groups the forelegs are raptorialand in others the hind legs are long and slender andbear rows of long swimming hairs. Larvae of someBrachycentridae have rows of hairs on the middle andhind legs used for filtering food particles from cur-rents. Tarsi have one segment and tarsal claws aresingle. In all families, the prothorax bears a pair ofheavily sclerotized pronotal plates. In some families,notably the Hydrospychidae and Hydroptilidae, themesonotum and metanotum are also heavily sclero-tized, but in other families these thoracic nota areentirely membranous or with lesser degrees of sclero-tization. The abdomen consists of 10 segments andis entirely membranous. It is usually bare except fora few scattered setae, but in the Hydropsychidae itis densely covered with short modified hairs and scalehairs. The abdomen lacks appendages except fora pair of short anal prolegs on the last abdominalsegment, each bearing a strong anal claw. In the

case-making Integripalpia, the first abdominal seg-ment usually bears dorsal and lateral humps. Abdomi-nal gills may or may not be present and have evolvedseveral times within the order. When present, they arefilamentous and may occur singly on one to severalabdominal segments, in tufts of many filaments, or ashighly branched stalks. They can occur in dorsolat-eral, lateral, and ventrolateral rows.

Pupae

Trichoptera pupae are of the exarate type, with theantennae, legs, and developing wings free from thebody. Mandibles are dectitious in most families, usu-ally cross each other apically, and point forward(Figure 4(b)). Antennae lay back above the thoraxand abdomen. In species with long antennae, theyare coiled around the end of the abdomen. The thoraxis unmodified, but the thoracic legs often have swim-ming hairs. The abdomen bears remnants of the larvalgills and has characteristic paired hook plates dor-sally that aid the pupa in exiting the pupal shelter.The abdomen ends in a pair of anal processes.


Phylogeny and Classification

The order Trichoptera is very well established as amonophyletic group whose members are derivedfrom a single common ancestor. Basal diversificationof Amphiesmenoptera (Lepidoptera þ Trichoptera)dates back at least to the Triassic, and basal diversifi-cation of existing lineages of Trichoptera dates backat least to the middle Jurassic. There is a rich Balticand Dominican amber fossil fauna.The order is divided into three suborders: Spicipal-

pia, or cocoon-makers, containing four families offree-living forms, tortoise case-makers, and pursecase-makers; Annulipalpia containing eight familiesof retreat-makers; and Integripalpia made up of 33families of portable case-makers. In the most recentphylogeny, based on a combination of morphologicaland molecular sequence data from several genes,monophyly of Annulipalpia and Integripalpia waswell supported, but monophyly of Spicipalpia wasequivocal. In this analysis, Spicipalpia was mostclosely related to Integripalpia (Figure 6).

Ecology

Life History

Trichoptera females lay eggs in or near the water.Females of most Spicipalpia and many Annulipalpiaenter the water for egg laying, either by crawling orswimming below the surface. The latter activityis facilitated by oar-like modifications of the mid-dle legs. Eggs are laid on or under submerged rocks,branches, logs, vegetation, etc., the exact placementfacilitated by the female’s ability to protrude andmove the oviscapt. Eggs are coated with spumulin, asticky gelatinous polysaccharide. They emerge fromthe female’s abdomen in long strings and are groupedin irregular masses on the substrate. In females ofmost Integripalpia, the eggs are formed into an eggmass as they leave the body. The egg mass is held atthe end of the abdomen prior to oviposition. Eggmasses in these species can be irregular, but in manyspecies they have characteristic shapes, either as flatspirals, spheres, pyramids, or other more unusualconfigurations. In these species, females are able tofly to oviposition sites where they attach the egg massto stones or other objects at the water’s edge; somefemales will enter the water to oviposit. Other integ-ripalpian females deposit the egg mass near or evenout of the water, on overhanging vegetation, forexample, where moisture from splash, rain, or dewwets the mass, causing the spumulin to swell andturn to liquid. The eggs or newly hatched larvae

then wash or fall into the water. The spumulin matrixcan protect the eggs from desiccation during dry con-ditions. Females can deposit one to several eggmasses, each containing a dozen to several hundredeggs, depending on the species. Female feedingenhances her longevity and fecundity. The egg stagelasts for only a few days, but extended egg diapausedoes occur.

Most of the life history of a caddisfly is spent in thelarval stage, which typically goes through five larvalinstars, although additional instars, sometimes wellover five, have been reported in some species. Thelarval stage is the active, feeding stage and all larvaehave well-developed mouthparts. Larvae are primarilydetritivorous, but predation is common. Herbivory isless common, and one putative case of parasitism inHydroptilidae has been reported. In Temperate Zones,the larval life lasts for several months and life cyclesare completed in a year. In warmer regions, or undercertain circumstances, two or more life cycles maybe completed within the year. Final instars of somespecies enter prepupal diapause in the sealed off larvalcase. In several families, the life cycle may takemore than a year to complete. Almost nothing isknown about life cycles of caddisflies in nonseasonaltropical regions.

Prior to pupation, the final instar larva of thecase-making families fixes its case to stable substrateand seals off the anterior opening with a silken,perforated cover; otherwise, the case is largelyunmodified. The silken cover protects the developingpupa from intrusion by predators or parasites. Pupalabdominal undulations also help draw a flow offresh, oxygenated water through the anterior silkenmesh and out the smaller posterior opening, thus,greatly facilitating pupal respiration. It is not unusualto find aggregations of dozens of pupae afixed in thesame location, on a rock or other suitable structure.Retreat-makers undergo a variety of pupation behav-iors. In most families, the last instar larva builds aseparate pupation chamber of small rock fragmentsor debris, lined internally with silk. Anterior andposterior perforated openings allow water to flowthrough and bathe the pupa directly. In other annuli-palpians, a loose silken cocoon is spun inside thepupal shelter; the cocoon can be free or variouslyattached to the inside of the pupal shelter. In thesefamilies, it is believed that the pupal cocoon is perme-able to water. The free-living families Rhyacophilidaeand Hydrobiosidae build a special dome-shaped, ovalpupal chamber of sand grains and rock fragments;other spicipalpians pupate within the modified larvalcase. Inside, the last larval instar of all spicipalpiansspins a rigid, thickened silken cocoon. It has been

Figure 6 Phylogeny of Trichoptera, with approximate numbers of known species and distribution by major biogeographic region.Phylogeny based on Kjer et al. (2002), showing only those nodes supported by bootstrap values arbitrarily set above 80% in either their

differentially weighted or equally weighted combined (molecular and morphological) analyses and/or nodes supported by at least two

independent data sets. Approximate numbers based on Trichoptera World Checklist and other sources. AT, Afrotropical; AU,

Australasian; NA, Nearctic; NT, Neotropical; OR, Oriental; PA, Palearctic.



demonstrated that this cocoon is semipermeable andthat an osmotic gradient occurs between the fluidinside the cocoon and the environment. The physicalstructure of the cocoon actively promotes diffusion;the depletion of oxygen within the cocoon driving thediffusion of fresh oxygen into the cocoon from oxy-gen rich waters, thus, the pupa receives more oxygenthan it would if diffusion were passive. The pupalstage lasts only a few weeks and is always aquatic.Upon maturation, the fully developed pupa uses itswell-developed mandibles to cut open the sealed caseor retreat and immediately swims or crawls to thesurface where the adult quickly escapes from thepupal cuticle. In fact, the mandibular muscles ofthe unemerged adult operate the pupal mandibles;the muscles atrophy soon after the adult sheds thepupal cuticle.Adults are usually crepuscular, with emergence

beginning most commonly at dusk and lasting forthe first few hours after sunset; there is a smallerperiod of adult emergence just before dawn. A fewspecies are diurnal. The newly emerged adultsare teneral, but soon harden. They quickly enter mat-ing swarms or engage in other mating behaviors.Mate attraction through species-specific sex phero-mones has been demonstrated in a number of species.Other courtship behaviors, including vibrationalcommunication and posturing have been observed,but have been little studied. In fact, little is known

Figure 7 Larvae of Spicipalpia. (a) Hydrobiosidae, genus Atopsyche

genus Protoptila.

about adult biology in general, as studies have con-centrated on the ecologically important larval stage.Mating takes place on the ground or on vegetation,but never in the air. Male and female abdomens arecoupled end-to-end during copulation. Adults feed onwater and sugary liquids, such as honeydew and nec-tar, and feeding positively affects adult longevity andfemale fecundity. Adults live for a few days to severalweeks, depending on the species, available foodsources, and environmental conditions.

Larval Construction Behavior and Feeding

In the Spicipalpia, there are several rather differentgroups, each with different larval habits and feedingstrategies, the free-living caddisflies, purse case-makers,and tortoise case-makers (Figure 7(a)–(c)). The free-living and predaceous families Rhyacophilidae andHydrobiosidae build no larval structures, except for aterminal shelter in which to pupate. They crawl on thebottom substrate and actively prey on other aquaticinvertebrates. They may lay down silken safety linesto anchor them to the substrate, in the event that thecurrent dislodges them. To complement their predatoryhabits, larvae of Hydrobiosidae have modified rapto-rial forelegs. Purse-case makers (Hydroptilidae, includ-ing Ptilocolepidae) are free living until the last larvalinstar (the fifth), and then construct a case, whichmay either be portable or cemented to the substrate,

; (b) Hydroptilidae, genus Byrsopteryx; (c) Glossosomatidae,

Figure 8 Larvae of Annulipalpia. (a) Philopotamidae, genus

Chimarra; (b) Hydropsychidae, genus Calosopsyche.


in which the larvae eventually pupate. Hydroptilidsundergo ‘hypermetamorphosis’ in which the first fourinstars are small and passed through rather quickly,while the case-making fifth instar resembles a moretypical caddisfly larva, except that the abdomen iscommonly very enlarged. The fifth instar is the primaryfeeding stage, holding the major food reserves for pupaland adult development. These are among the smallestof caddisflies, as reflected in the commonly used name‘microcaddisflies.’ Fully grown larvae and adults areusually no more than 5mm or so, and some muchsmaller. Hydroptilid larvae build a variety of casesthat converge on three main types. These include themore common ‘purse cases,’ consisting of two flattenedsilken valves often covered with fine detritus, sandgrains, filamentous algal strands, or pieces of foliosealgae. The valves are joined dorsally and ventrally,forming a residence for the larva. Other hydroptilidsbuild an oval, flattened, fixed, retreat-like case. In thefinal group, tubular cases similar to those of Integripal-pia are constructed, but these are thought to be amodification of the purse-case. Hydroptilids feed bycollecting fine organic matter or by scraping diatomsfrom rock surfaces. The more specialized hydroptilidspierce algal cells and suck out the cell contents or feeddirectly on liverworts. The tortoise-case or saddle-casemakers comprising members of the family Glossoso-matidae make a case that is constructed very much likethe pupal cases of Annulipalpia and the free-livingSpicipalpia, consisting of a dome of small sand grainsand pebbles. However (to complete the analogy to atortoise), the larva also makes a transverse strapbeneath the dome, allowing the larva to carry it on itsback. The tortoise-case makers construct a new andbigger case with each larval instar, and then pupatewithin a cocoon within the last larval case, after remov-ing the ventral strap and attaching the case to thesubstrate. Glossosomatids are universally scrapers ofperiphyton – the diatoms, other algae, and fineorganic ooze that grows and settles of the surfacesof submerged rocks and other substrate.All of the families whose larvae make retreats and

capture nets of silk are members of the Annulipalpia(Figure 8(a) and 8(b)). These families are usuallyrestricted to running water, from torrential currentsto slow moving channels, but some occur in standingwaters. Larval annulipalpians build a stationaryretreat, and at or near its entrance spin a silken cap-ture net, used to filter the water of fine organic mate-rial. The larvae glean the net of food particles withtheir mouthparts. Some species live within a modifiedportion of the net itself. Others capture living inverte-brate prey that contact the silken webbing, whereas afew build filtering tubes buried in sandy substrates. Inthe net-spinning species, nets are spun and repaired

with fine silken strands, extruded from the labium.In some, the labium is modified to produce multiplestrands. Mesh diameters vary from a few to several100 mm, depending on the species, allowing species tospecialize on different sized food particles. In someannulipalpian families, larvae live within a fixed, ser-pentine, silk-lined detritus tube and feed on fine sur-face deposits or periphyton.

The Integripalpia have been called the tube case-makers, because they most commonly construct atubular case (Figure 9(a) and 9(b)). The case, how-ever, can be made from very different materials orformed in peculiar ways in various species. The larvaeare mobile and simply extend or add to the case witheach larval instar, eventually pupating inside theslightly modified larval case. It is in this suborderwhere some of the most remarkable examples ofinsect architecture occur. Cases can be made entirelyof transparent or smooth, darkened silk, but mostoften they are fashioned of rock or plant fragmentsor both (Figure 10(a)–(k)). Unusual materials arealso used, including snail opercula, entire snail shells,discarded cases of other caddisflies, pieces of fresh-water sponges, and small bits of charcoal, amongother items. Cases can be very long and slender orshort and compact. They often have larger stonesincorporated along the sides. Although most com-monly round in cross section, some are flattened dor-soventrally, hiding the larvae from above, or aresquare. They often have slender twigs or conifer

Figure 9 Larvae of Integripalpia. (a) Limnephilidae, genus

Limnephilus; (b) Leptoceridae, genus Nectopsyche.


needles trailing off the ends. More than a few specieshollow out a twig to use as a case and a few use theabandoned cases of other caddisflies. Although eachstone or plant part is carefully selected and positionedduring construction, there is generally no particularpattern to the pieces, except in those species that build‘log-cabin’ cases or in those that arrange the pieces ina gentle spiral. The case materials can be randomlysized or be very uniform and there is often a fidelityfor particular materials, especially among localizedpopulations. In an entire family, the Helicopsychidae,the species make cases that resemble snail shells.There seems to be no end to the imagination of thecase-makers! Larvae of Integripalpia are commonin both standing and running waters. In north tem-perate lentic habitats, they are the dominant group,particularly the large, diverse family Limnephilidae.Another case-making family, the long-horned caddis-flies, or Leptoceridae, is a dominant family in tropicalregions. Cases probably evolved to provide protec-tion from predators, perhaps as camouflage, but morelikely as physical protection from crushing by fishjaws. It has been demonstrated that the case alsoserves a respiratory function. Larvae residing withinthe cases undulate their abdomens, thus, drawingwater through the anterior opening and out the

small posterior opening of the case. The currentbathes the gills with a fresh supply of oxygenatedwater and expels spent water from the case. It hasbeen hypothesized that the ability of larvae to regu-late respiration has allowed the case-makers toexploit standing water or warmer flowing waterswhere the concentration of dissolved oxygen islower. This hypothesis holds that the ancestral habitatwas cool, highly oxygenated mountain streams. Case-making larvae are primarily detritivores. They feed byshredding and ingesting leaves and other plant partslargely of riparian origin. After entering the water,leaves undergo a short period of conditioning andare then colonized by bacteria, fungi, and othermicroorganisms that begin the decay process. It isthis microflora that is assimilated as food by theshredding caddisflies. The process of shredding andsubsequent defecation, as well as mechanical break-age, processes detritus into finer and finer organicmaterial that becomes available to other groups,such as filter-feeding caddisflies and those that collectand gather fine detritus from the bottom. Predation isalso common among the case-makers, but herbivoryon living plants is less common. Other case-makersfeed by scraping the diatoms, other algae, and finedetritus that make up the periphyton. A very few arefilterers. One unusual group of leptocerids in thegenus Ceraclea feeds on freshwater sponges. Mem-bers of the rare family Atriplectididae specialize asscavengers on dead aquatic invertebrates, and somelimnephilid shredders feed on salmon carcasses.Through these diverse feeding strategies, caddisfliesare fundamental participants in nutrient dynamicsand energy flow in aquatic systems.

Larval Habitats

Trichoptera larvae, with very few exceptions, areaquatic, and are found in an impressive array ofhabitats (Figures 11–13). In a few rare instances,larvae of some species are terrestrial, but neverthelessassociated with moist riparian habitats. Some ventureinto brackish water, but the remarkable members ofthe family Chathamiidae from New Zealand andAustralia are unusual for the Insecta in having larvaethat are truly marine, mostly restricted to tidal pools.Species occur primarily in permanent waters, butthose that live in vernal pools or in seasonally drystreams have adaptations in the egg, larval, and pupalstages for withstanding desiccation of the habitat.A southeastern Brazilian species lives in bromeliadtanks. Larvae are known from thermal springs, butare generally absent from highly acidic or highlyalkaline waters, although species are known fromsphagnum bogs and calcareous springs. Larvae occur

Figure 10 Cases of caddisfly larvae. (a) Brachycentridae, genus Adicrophleps; (b) Calamoceratidae, genus Heteroplectron;(c) Goeridae, genusGoeracea; (d) Apataniidae, genus Pedomoecus; (e) Hydroptilidae, genus Palaeagapetus; (f) Helicopsychidae, genus

Helicopsyche; (g) Leptoceridae, genus Amazonatolica; (h) Limnephilide, genus Grammotaulius; (i) Phryganeidae, genus Fabria;

( j) Sericostomatidae, genus Grumicha; (k) Leptoceridae, genus Triaenodes.


in springs and seeps, torrential mountain streams, andlarge, lowland rivers. They occur in large lakes, ponds,and marshes. Species can also be found in the thin filmof water that flows over rocks as well as the splash zoneof streams and waterfalls. They occur on or in thebottom substrate, on submerged twigs and branches,and among submerged aquatic vegetation. The diversityof microhabitats exploited by caddisfly larvae is a con-sequence of the many ways silk is used to construct

retreats, nets, and cases and probably accounts for thesuccess of the order as a whole.

Economic Importance

As ubiquitous and abundant organisms, Trichopteralarvae are important and beneficial components of thetrophic dynamics and energy flow in the lakes, rivers,and streams they inhabit. These freshwater aquatic

Figure 11 Example of Trichoptera habitat. Rio Soberbo, Parque Nacional Serra dos Orgaos, Rio de Janeiro, Brazil.

Figure 12 Example of Trichoptera habitat. Hamma Hamma River, Olympic National Forest, Washington, USA.


Figure 13 Example of Trichoptera habitat. Walker Bay, Leech Lake, Minnesota, USA.


habitats are among the most severely impacted andenvironmentally threatened in the world, because theyreceive and amplify abuses to the landscape, includingsuch effects as sedimentation; pollution from industry,mining, and agriculture; sewage contamination; acidrain; and water diversion for agricultural and metro-politan uses. Trichoptera are considered among themost useful and important aquatic organisms formonitoring these effects and are widely used in bio-monitoring surveys, many of which are now man-dated by federal and municipal statutes in developedcountries, but are increasingly being seen as an inex-pensive and effective tool in developing countries.However, the latter implementation is hampered bya lack of knowledge of the larval stages.In their role as food for trout and other fish, all life-

history stages serve as models for dry and wet fliesused in fly fishing, resulting in a multimillion-dollarcommercial activity. Izaak Walton in The CompleatAngler mentioned caddisflies and several importantflies, such as theWhite Miller, are modeled after adultcaddisflies. A small cottage industry also exists incaddisfly jewelry. Larvae of certain case-makers keptin aquariums containing precious stones and nuggets,such as turquoise, red coral, and ornamental glass,will fashion their cases out of these materials. Casesare then preserved after pupal emergence and madeinto earrings, necklaces, and bracelets. Among some

indigenous groups in Brazil, larval cases are collectedfrom the wild and used in adornments.

Caddisfliesmay emerge by the thousands from riversand lakes under certain conditions, especially onwarm,humidnights, and are readily attracted to lights. In fact,the use of lights, especially UV lights, is a standardmethod of attracting adults for collecting (Figure 14).If mass adult emergence occurs in urban waterways,especially near public facilities such as outdoor sta-diums, they can create a nuisance. More serious,though, is the respiratory allergic reaction that somepeople have to caddisfly hairs; these are easily rubbedoff the wings and become airborne.

Caddisfly larvae play only a minor role as agricul-tural pests, most notably the herbivorous species thathave caused damage by feeding on rice in Asia andwatercress in Europe. The larva of a hydropsychidhas been implicated in the failure of bridge pilings inVirginia. The constant activity of generations of lar-vae gouging out small depressions in the wood inwhich to build their retreats resulted in weakeningof the pilings.

See also: Aquatic Ecosystem Services; Aquatic Insects –Ecology, Feeding, and Life History; Aquatic Insects,Classification; Benthic Invertebrate Fauna, Lakes andReservoirs; Benthic Invertebrate Fauna, River and Flood-plain Ecosystems; Benthic Invertebrate Fauna, Small

Figure 14 Collecting caddisfly adults at night, Bolivia.


Streams; Benthic Invertebrate Fauna, Tropical StreamEcosystems; Benthic Invertebrate Fauna, Wetland Eco-systems; Benthic Invertebrate Fauna; Bioassessment ofAquatic Ecosystems; Biodiversity of Aquatic Ecosys-tems; Lakes as Ecosystems; Regulators of BioticProcesses in Stream and River Ecosystems; Streamsand Rivers as Ecosystems; Trophic Dynamics in AquaticEcosystems.

Further Reading

Betten C (1934) The caddisflies or Trichoptera of New York State.

Bulletin of the New York State Museum 292: 1–576.Blahnik RJ and Holzenthal RW (2004) Collection and curation of

Trichoptera, with an emphasis on pinned material.Nectopsyche,Neotropical Trichoptera Newsletter 1: 8–20.

Kjer KM, Blahnik RJ, and Holzenthal RW (2002) Phylogeny ofcaddisflies. Zoologica Scripta 31: 83–91.

Kristensen NP (1997) Early evolution of the Lepidoptera þTrichoptera lineage: Phylogeny and the ecological scenario. In:Grandcolas P (ed.) The Origin of Biodiversity in Insects: Phylo-genetic Tests of Evolutionary Scenarios, pp. 253–271.Memoiresdu Museum National d’Histoire Naturelle 173.

LaFontaine G (1981) Caddisflies. New York, NY: Nick LyonsBooks.

Mackay RJ andWiggins GB (1979) Ecological diversity in Trichop-

tera. Annual Review of Entomology 24: 185–208.

Malicky H (1973) Trichoptera (Kocherfliegen). Handbuch derZoologie, Band IV, Halfte 2, Teil 2/29. Berlin: Walter de Gruyter.

Merritt RW, Cummins KW, and Berg MB (eds.) (2008) An In-

troduction to the Aquatic Insects of North America, 4th edn.Dubuque: Kendall/Hunt Publishing Company.

Morse JC (1997) Phylogeny of Trichoptera. Annual Review ofEntomology 42: 427–450.

Ross HH (1944) The caddis flies, or Trichoptera, of Illinois.

Bulletin of the Illinois Natural History Survey 23: 1–326.

Ross HH (1967) The evolution and past dispersal of the

Trichoptea. Annual Review of Entomology 12: 169–206.Schmid F (1998)Genera of the Trichoptera of Canada and Adjoin-

ing or Adjacent United States. Ottawa: NRC Press.

Wallace JB andMerritt RW (1980) Filter-feeding ecology of aquatic

insects. Annual Review of Entomology 25: 103–132.Wiggins GB (1996) Larvae of the North American Caddisfly

Genera (Trichoptera). Toronto: University of Toronto Press.

Wiggins GB (2004) Caddisflies, the Underwater Architects.Toronto: University of Toronto Press.

Relevant Websites

http://tolweb.org/Trichoptera/8230 – The Tree of Life, Trichoptera

pages

http://entweb.clemson.edu/database/trichopt/index.htm – Trichop-tera World Checklist

http://www.entomology.umn.edu/museum/links/news.html –Necto-psyche, Neotropical Trichoptera Newsletter

http://tolweb.org/Trichoptera/8230

http://entweb.clemson.edu/database/trichopt/index.htm

http://www.entomology.umn.edu/museum/links/news.html

encyclopedia of inland waters || trichoptera (caddisflies)

Documents