Eastern tent caterpillars Malacosoma americanum live in larg

Eastern tent caterpillars (Malacosoma americanum) live in large groups in silk nests, or tents, which they build in trees. They are among the first insects to be active in the early spring when daily temperatures fluctuate from freezing to very hot. Over the course of a day, they display striking differences in behavior: Early in the morning, they rest in a tightly packed group on the tent\'s east facing surface. In mid-afternoon, they are on its undersurface, each caterpillar hanging by a few of its legs. Propose a hypothesis to explain this behavior. How could you test it?

Solution

basically this behavior is directly related to boby temperature adjustment. Tent is constructed by caterpillar in the crotch of the host tree and is typically oriented with the broadest wall facing the southeast to take advantage of the morning sun as early morning temperature is low. as SUN rises the temperature starts rising and the behavior changes as follows: Light has a great effect on the caterpillars while they are spinning, and they spin the majority of their silk on the most illuminated face of the tent. Because the early spring weather is often cold, the caterpillars rely on the heat of the sun to elevate their body temperatures to levels that allow them to digest their food. . Early instars are black and their bodies readily absorb heat. When basking, they typically pack together tightly, reducing heat loss due to convective currents. Their long setae serve to stem convective heat loss. The caterpillars may aggregate on the surface of the tent or within it. The tents act as miniature greenhouses, trapping the heat of the morning sun and allowing the caterpillars to warm more quickly than they would if they remained outside. An aggregation of basking caterpillars can achieve temperatures in excess (T_bodyT_ambient) of 44 °C. They easily overheat, so the aggregation splits up when they reach a satisfactory temperature.

Because of layered structure, the TENT is thermally heterogeneous, and the caterpillars can adjust their temperature by moving from layer to layer. They may also aggregate on the outside of the shaded side of the tent and hang from the tips of their abdomens to enhance convective heat loss and cooling.