Chionea albertensis

Chionea albertensis is distinguished from other Chionea species by geographic distribution and presumably by subtle morphological characters used in Alexander's original description (1941). The sixteen North American Chionea species are generally similar in appearance; accurate identification to species level requires examination of specimens by a specialist. Western species including C. albertensis are mostly confined to mountain ranges, whereas eastern species occur more broadly in forested areas. The species is smaller than winged crane flies and may be confused with other wingless insects such as grylloblattids (rock-crawlers), but differs in body form and habitat use.

Mountain ranges of western North America. Adults are found on snow surfaces but spend most of their time concealed in subnivean microhabitats: cavities beneath snow created by arching grass blades, leaf litter, and small mammal tunnels. These insulated environments provide milder temperatures than surface conditions. Also reported from fairly deep in caves.

Western North America: Canada (Alberta, British Columbia) and USA (south to Oregon, Idaho, and Montana). Nearctic region.

Active during winter months. Chionea species generally appear most commonly in October and November, and again in February and March. Adults may live up to two months.

The life cycle remains incompletely known. Adults are present in winter. Eggs are laid singly; females can produce up to 194 eggs. Eggs take eight days to three weeks to hatch under laboratory conditions. Larvae feed and grow during summer months, with pupation in fall. Larval diet is unknown; rearing attempts in laboratory have failed. Larvae have fairly hardened mouthparts suggesting ability to consume solid food.

Adults crawl on snow surfaces during winter, making them conspicuous despite normally cryptic habits. Occupies subnivean environment to avoid freezing. Has glycerol in body fluids acting as antifreeze, and modified enzyme systems allowing function at low temperatures. Susceptible to overheating. Every attempt to rear in laboratory has failed.

Prey for small mammals (mice) and grylloblattids (rock-crawlers). Serves as intermediate host for parasitic tapeworms of rodents: tapeworm eggs consumed by snow fly larvae develop to cysticeroid stage, then transmitted to rodents when snow flies are eaten.

Does not bite or sting humans. Encountered by hikers and naturalists in winter mountain environments. Subject of scientific interest due to cold adaptation mechanisms. No economic importance documented.

• Other Chionea speciesSixteen North American species are morphologically similar; C. albertensis distinguished by western mountain distribution and subtle morphological characters from Alexander's 1941 description
• Grylloblattidae (rock-crawlers)Also wingless, cold-adapted, and found at high elevations in western North America, but differ in body form and are predatory on snow flies rather than competing with them
• Snow fleas (Collembola, Hypogastrura nivicola)Also active on snow in winter but are springtails (non-insects in traditional sense), much smaller, and use different locomotion (furcula for jumping)

Snow flies are sometimes confused with snow fleas (springtails), but they are unrelated and differ in behavior and taxonomy. They do not bite or sting despite occasional public concern.

• wingless
• winter-active
• subnivean
• cold-adapted
• mountain
• western North America

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Bug Eric: Fly Day Friday: Snow Flies