Answer:
Caterpillars are in a semi-hibernation phase
Step-by-step explanation:
During winter caterpillars dehydrate themselves and generate a cryoprotectant that flows in their circulatory system (i.e., hemolymph) to avoid water freezing, thus preventing tissue damage. For example, Pyrrharctia Isabella (Lepidoptera, Erebidae), a caterpillar common in North America, can survive 1 week at −20°C. This condition is known as 'semi-hibernation' and it ends when the first temperate days arrive.