rock crawler, name applied to the slender, wingless insects of the family Grylloblattidae in the order Orthoptera. They have long antennae and range in length from 1/2 to 1 in. (15–30 mm). Rock crawlers occur at altitudes of 1,500 to 6,500 ft (450–2,000 m), where they live in caves, under rocks, or on snow and ice; they thrive at temperatures just above freezing. They appear to be nocturnal and omnivorous. Rock crawlers were not discovered until 1911, and only five species are now known in the United States. Other species occur in Canada, Japan, and Siberia. They are very primitive insects, considered closely related to the basic stock from which the Orthoptera (including the cockroaches, mantids, and locusts) arose. Rock crawlers are classified in the phylum Arthropoda, class Insecta, order Orthoptera, suborder Grylloblattodea, family Grylloblattidae.