Explanation of Names
Trichoptera means "hairy wing", from the Greek "trichos" (a hair) + "pteron" (wing; feather)
Caddis means cotton or silk; tape or ribbon of worsted yarn. The name may have derived from
Caddice Men who were English vendors of ribbons, braids, and other miscellanea. They pinned their wares on their coats, not unlike the caddis larva that patches together its case
(1).
Numbers
Nearctica.com lists 23 families for North America.
Insects of Cedar Creek states there are 1,262 North American species in 18 families.
University of Saskatchewan states there are more than 1,350 species in 22 families in North America, and more than 7,000 species worldwide
Identification
Adults resemble moths, but wings are hairy instead of scaly.
Forewings usually dark, sturdy, sometimes with striking color patterns, held tightly together roof-like over the abdomen when at rest.
Hindwings often clear, relatively delicate, and hidden under forewings when at rest.
Antennae usually very long, threadlike, with many segments.
Chewing mouthparts with prominent palpi.
Tarsi have five segments.
Ocelli (simple eyes) present in some families.
Arnett
(2) gives a key to adult families in North America. Some genera can be keyed by distinctive features of the larval case.
The aquatic larvae have three pairs of legs and a soft, elongate, segmented abdomen usually hidden inside a case; head well-developed with chewing mouthparts in most species.
Most species live in a mobile case constructed from plant material, algae, grains of sand, pieces of snail shells, or entirely of silk. The case is held together with strands of silk secreted by the larva. In some species the case is attached to a rock, log, or other underwater surface; a few species have no case and are free-living.
The case's particular shape and construction material is distinctive of the family and/or genus, and can be used in identification. Example: Helicopyschidae larvae use sand grains to build spiral cases that resemble small snail shells.
Range
throughout North America and the world
Habitat
Species most diverse in well-aerated streams, but also occur in lakes, ponds, and marshes. Adults rest on nearby vegetion during the day; flight activity begins at dusk. Adults are attracted - sometimes in great numbers - to artificial light.
Season
adults fly from April to November
Food
Some adults take liquid food, such as nectar. Some do not feed. Larvae are usually detritivores, sometimes predators.
Life Cycle
Complete (holometabolous) development: egg, five-instar larva, pupa, adult. Usually one generation per year, sometimes multiple generations, and some species take more than a year to develop.
In some species, adults live for 30 days or more; in others, adults are short-lived.
Remarks
Larvae are an important food item of fish, and are used as bait by anglers.
Most caddisfly larvae are intolerant of pollution; therefore, their presence is an indication of good water quality, and their absence in areas where they previously occurred may be an indication of polluted water.
The fungus
Erynia rhizospora infects adult caddisflies and causes them to die stuck to the undersides of rocks and logs in streams. See
this article for some examples.
See Also
Lepidoptera, butterflies and moths--have scaly wings, a coiled
proboscis
Internet References
Trichoptera World Checklist (Clemson U., South Carolina)
overview of family including photos of all life stages, description, numbers, habitat, biology etc. (U. of Saskatchewan)
pictorial guide to larvae - identification of 6 families (New York State Dept. of Environmental Conservation)
