Forest Tent Caterpillar Moth - PC

Background
The Forest Tent Caterpillar Moth (Malacosoma disstria) is a North American moth, typically found in the eastern regions of the United States and Canada. They are black, dark brown or grey, with blue and yellow stripes, and are typically around 2 inches in length. Each abdominal segment has a white spot, which is covered by fur-like bristles known as 'setae'. The adult moth that emerges after pupation is yellow or tan with a thick, short, furry body. The wingspan of the moth is about 1.5 inches.

Thermoregulation
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. Increasing 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.