ABSTRACT

T is small group of 20 species represents the last of n ancient line of insect development that prob-bly links together many of the following orders of insects known as the orthopteroids, although currently there is little evidence for this assumption. Their Latin name implies that they look like a combination of a cricket and a cockroach. They were so named to show their relationship to these two groups, but the matter is far from setded. Their English common name refers to their wingless condition and the fact that they live among rocks, usually at high altitudes in Siberia, Japan, and North America, the only regions of the world where they have been found.