Trichoptera

Article By:

Holzenthal, Ralph W. Department of Entomology, University of Minnesota, St. Paul, Minnesota.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.709000

Caddisflies, one of five orders of insects with immature stages that are wholly confined to freshwater aquatic habitats. Like the hemimetabolous nymphs of mayflies (Ephemeroptera), stoneflies (Plecoptera), and dragonflies (Odonata), and the holometabolous larvae of fishflies and alderflies (Megaloptera), the larval and pupal stages of caddisflies are found in ponds, lakes, rivers, and streams around the world. In fact, caddisflies comprise the most diverse insect order whose members are exclusively aquatic. A few species in the family Chathamiidae from New Zealand and Australia are unusual insects because they have larvae that are truly marine, mostly restricted to tidal pools. A few others are found in brackish waters or in semiterrestrial habitats, but these, again, are exceptions. More than 13,000 species of Trichoptera have been described and placed in about 45 families and approximately 600 genera. They are found in high mountain lakes and glacial headwater streams, although they are rarely found at the highest elevations [more than 3000 m (9840 ft)]. The midreaches of rivers and streams probably harbor the most species diversity, especially in mountainous regions, but larvae are found in seeps, springs, torrents, lotic (flowing water) pools, and meandering lowland rivers, as well as adjacent to waterfalls. In standing waters, they are especially diverse in temperate marshes, ponds, and lakes, occurring even on the rocky, wave-washed shores of very large lakes. Specialized aquatic habitats include temporary ponds, hygropetric (thin water film) outcrops, and even the water-filled reservoirs held in the leaf axils of epiphytic bromeliads. See also: Insecta

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