The Forest Tent Caterpillar Moth (Malacosoma disstria) is a moth originating from North America, found throughout the United States and Canada, especially in the eastern regions. It is typically 2 inches in length with black, dark brown, or gray, with blue and faint yellow longitudinal stripes. Each abdominal segment bears a white spot, which are covered with fur-like lonfuckg "setae" (bristles). The adult moth that emerges after pupation is yellow or tan with a thick, short, furry body. The wingspan is about 1.5 inches.
Forest tent caterpillars are ectotherms so they rely on external sources of heat to raise their body temperatures. In order to do this, they bask together and benefit from group thermoregulation. Elevating body temperature is essential in increasing metabolic rates for movement and food processing, so proper thermoregulation leads to an increased rate of development. This is very important for M. distria caterpillars, which rely on fast growth in spite of low environmental temperatures in North America to benefit from the high food quality and the smaller predation risk in the spring. Thus, it is an adaptive advantage to bask in groups. However, as caterpillars grow, thermoregulatory needs decrease and the benefit of group living is gradually overridden by other factors such as food competition; if they bask in groups, the competition for food grows high, and therefore they do not bask in groups later on in their life.