ROCK-CRAWLERS (GRYLLOBLATTODEA) OF
R. A. Cannings and G. G. E. Scudder
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Family Grylloblattidae (Rock-crawlers)
As there is only one family in the Grylloblattodea the characters listed above for the order, also serve to describe the family Grylloblattidae.
Rock-crawlers are night active predators, that are usually considered to be primarily alpine or subalpine hypolithon inhabitants. However, they have been collected at lower altitudes in forested and unforested habitats. They even occur in permanent ice-caves in desert habitats in western North America.
Worldwide there are four genera and 25 species, confined to western North America, Siberia, Japan, China and Korea. One genus Grylloblatta with 11 species occurs in North America, with two species in Canada and British Columbia. Grylloblatta campodeiformis Walker, exits in the form of three subspecies in British Columbia. G. campodeiformis campodeiformis Walker is the most widespread, occurring from the Rocky Mountains to the Kamloops area. While an alpine or subalpine inhabitant over most of this range, it has also been collected in uncut, partial-cut and clear-cut subalpine spruce-fir and lower elevation cedar-hemlock forests in the Columbia Mountains and Highlands, and Thompson-Okanagan ecoregions, as well as in talus slopes at the base of Mt. Paul in Kamloops. G. campodeiformis athapaska Kamp is known only from Mt. St. Paul in Stone Mountain Provincial Park, while G. campodeiformis nahanni Kamp is known only from Mt. McDome and the nearby Limestone Peak in the Cassiar Range. Grylloblatta scudderi Kamp is only known from Mt. Garibaldi. In alpine habitats, the rock-crawlers are usually found at the edge of glaciers or snow-fields. No doubt they prey upon small arthropods living in such habitats, but most often they are encountered at night, when they come out and forage on the insects trapped on the ice or snow surface. These rock-crawlers are definitely cold-tolerant, and have been shown experimentally to have a preferred temperature at 90-99% relative humidity of -3.5°C to +5°C, with an optimum at +1.67°C. They are long lived insects, evidently taking several years to complete the life history.