Grylloblattodea

Pronunciation:  [GRIL-o-bla-TOE-dea]

Common Name:  Rock Crawlers / Icebugs

Greek Origins of Name:  Grylloblattodea, derived from the Greek “gryll” meaning cricket and “blatta” meaning cockroach, refers to the blend of cricket-like and roach-like traits found in these insects.

Spot ID Key Characters:

  1. Body cylindrical, wingless
  2. Mouthparts mandibulate, hypognathous
  3. 5-segmented tarsi
  4. Cerci long, 8-segmented

Development:  Hemimetabola, i.e. incomplete metamorphosis (egg, nymph, adult)
Taxonomy:  Orthopteroid, closely related to Orthoptera and Dermaptera
Distribution:  Rare. Found in caves or near ice or snow at high elevations in mountains of Asia and North America.  Approximately 1 family and 11 species in North America and 1 family and 25 species worldwide

Rock crawlers are a small and obscure group of insects found only at high elevations in the mountains of China, Siberia, Japan, and western United States and Canada. Cave-dwelling species have been found in Korea and Japan. These omnivorous insects scavenge for food on the surface of snowfields, under rocks, or near melting ice. They are active only at cold temperatures and move downward toward permafrost during warm seasons. As their ordinal name implies, rock crawlers have a blend of physical characteristics from both crickets (gryllo-) and cockroaches (blatta-). Some taxonomists include these insects as a suborder or family within Orthoptera. Others believe these insects are the only survivors of a primitive lineage that gave rise to other orthopteroid orders.

Appearance of Immatures and Adults:

  1. Antennae slender, filiform
  2. Mouthparts mandibulate, hypognathous
  3. Body cylindrical
  4. Tarsi 5-segmented
  5. Secondarily wingless
  6. Cerci long, 8-segmented

Rock crawlers have no economic importance. They live in places that are not inhabited by humans.

Grylloblattidae is the only family in this order. It contains four genera but only one (Grylloblatta) is found in North America.

  • Rock crawlers were first discovered around 1906; the first formal description of the order was published in 1915.
  • With only 25 species described worldwide, Grylloblattodea is the second smallest order of insects.  Mantophasmatodea is the only order with fewer species.
  • Rock crawlers cannot tolerate warm temperatures.  Most species are active below freezing and usually die above 10 degrees Celsius.
  • Due to the cold temperature at which they live, growth and development is very slow.  Rock crawlers may require up to seven years to complete a single generation.
  • No grylloblattids have ever been found in the Southern Hemisphere.