Rock Crawlers, Order Grylloblattodea

Habits and Traits of Rock Crawlers, Ice Crawlers, and Ice Bugs

Rock crawler.
A very rare ice crawler. Alex Wild (public domain)

The order Grylloblattodea is not well known, due in part to the small size of this insect group. Commonly called rock crawlers, ice crawlers, or ice bugs, these insects were first described in 1914. The order name comes from the Greek gryll for cricket and blatta for cockroach, a testament to their odd mixture of both cricket-like and roach-like traits.

Description:

Rock crawlers are wingless insects with elongate bodies ranging from 15 to 30 mm in length.

They have either reduced compound eyes or none at all. Their long, slender antennae may have as many as 45 segments, but no less than 23, and are filiform in shape. The abdomen ends with long cerci of 5 or 8 segments.

The female rock crawler has a pronounced ovipositor, which she uses to deposit eggs individually in the soil. Because these insects live in such cold habitats, their development is slow, taking as many as 7 years to complete a full life cycle from egg to adult. Ice crawlers undergo simple metamorphosis (egg, nymph, adult).

Most ice bugs are believed to be nocturnal. They're most active when temperatures are coldest, and die when temperatures rise above 10º Celsius. They scavenge on dead insects and other organic matter.

Habitat and Distribution:

Rock crawlers inhabit the earth's coldest environments, from ice caves to the edge of glaciers They typically live at high elevations.

We know of only 25 species worldwide, and 11 of these live in North America. The other known ice bugs live in Siberia, China, Japan, and Korea. So far, rock crawlers have never been found in the southern hemisphere.

Major Families in the Order:

All rock crawlers belong to a single family – Grylloblattidae.

Families and Genera of Interest:

  • Grylloblattia campodeiformis was the very first rock crawler discovered. E.M. Walker described the species, which was found in Banff, Alberta (Canada).
  • The genus Grylloblattina includes just one species, which lives in Siberia.
  • All North American ice bugs belong to one genus, the Grylloblattia.

 

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