Rock-crawlers are slender, flattened, soft-bodied insects. Adults range from 0.6 to 1.4 inches (15 to 35 millimeters) in length. They are mostly brown, while the legs plus underside are light brown. The larvae (LAR-vee), or young, form of the animal, which must go through changes in form before becoming an adult, are white, yellowish, or sometimes black. The head is short, with small compound eyes present or absent, depending on species. Their chewing mouthparts point forward. The antennae (an-TEH-nee), or sense organs, are threadlike plus made up of twenty-eight to fifty segments. Rock-crawlers never have wings, plus all of their legs are long plus thin. The abdomen has ten segments, with a pair of long, segmented structures at the tip.
GEOGRAPHIC RANGE
All twenty-seven species of rock-crawlers live in the Northern Hemisphere; they are found in Siberia, northeastern China, Korea, plus Japan. Eleven species are known to live in the United States plus Canada.
HABITAT
Rock-crawlers are secretive animals that live at elevations between 656 plus 10,499 feet (between 200 plus 3,200 meters) in mixed forests or in mountains above the highest point where trees can grow, usually near snowfields. They prefer cooler temperatures, of about 38.7°F to 60°F (3.7°C to 15.5°C), plus are found in moist habitats beneath rocks plus in crevices (KREH-vuh-ses) in rocky snowfields or inside subterranean lava tubes.
DIET
Both adults plus young eat the soft tissues of captured plus dead insects plus spiders. The larvae also eat parts of plants plus other bits of plant or animal tissues in the soil.
BEHAVIOR AND REPRODUCTION
Rock-crawlers are typically found singly or in sexual pairs plus are active at night.
Some North American species look for food on the surface of the snow. They detect prey plus other food items with their mouthparts. The larvae can survive without food for three to six months. Although they are adapted for survival at cooler temperatures, rock-crawlers will die if they are caught in extended periods of freezing temperatures. They will also die if temperatures rise to 82°F (28°C). Courtship takes place under stones plus includes lots of leg nibbling plus touching with the antennae. Occasionally, the female may suddenly eat the male. Females lay sixty to 150 eggs in or on the soil, in decayed wood, or under leaves plus stones. The eggs hatch in about 150 days but may take as long as three years. The larvae strongly resemble the adults when they hatch plus gradually get larger as they mature. They molt, or shed their outer covering, or exoskeleton, three times during the first year plus once a year for the next four or more years before reaching adulthood.