Other Common Names
Snailcase Caddisflies, Snail Case Caddisflies, Snail Case-making Caddisflies, Snail-shell Caddisflies
Explanation of Names
Helicopsychidae Ulmer 1906
Numbers
7 species in 1 genus in North America (9 species are listed at
nearctica.com but two of those (
Helicopsyche annulicornis and
arenifera) are synonyms of
H. borealis)
1 species (Helicopysche borealis) in Canada
203 described species world-wide in 2 extant genera and 2 extinct genera
Size
adult body 5-7 mm
larval case to 7 mm diameter
Identification
The spiral "snail shell" shape of the larval case is diagnostic (
photo) - as is the strongly curved "J" shape of the larva (
photo)
Adults are brownish or mottled, similar to adults of some other families of small caddisflies
Range
most of United States and southern Canada, north to Northwest Territories [see
Helicopsyche genus page for distribution of species]
also occurs in many warmer regions of the world
Habitat
larvae usually live in fast-flowing streams and rivers, but also shallow areas of lakes, thermal springs, and deep within the streambed; tolerant of various habitats and a range of water temperatures; larvae often found clustered together on rock surfaces
adults usually found near larval habitat; they are nocturnal and attracted to light
Food
larvae scrape diatoms and detritus from underwater surface of substrate
Internet References
"The Helicopyschidae Home Page" includes links to species list, systematics, distribution, photos, description (Swedish Museum of Natural History)
live larva and case images plus description, habitat, and other info (Valley City State U., North Dakota)
larval case image (James Harrington, California Dept. of Fish and Game)
larva and case images of
Helicopysche borealis by Cheryl Podemski, plus description and other info (Hugh Clifford, U. of Alberta)
common name reference [Snail-shell Caddisflies] plus photos and overview of
Helicopsyche borealis (Wilfred Laurier U., Ontario)
technical description of larva, adult, and genitalia, plus distribution and other info (Government of Canada)
images of larva, case, adult of unidentified
Helicopsyche species (South Dakota State U.)
world distribution map (Swedish Museum of Natural History)