the use of an insect is particularly significant because of all the things in this world, the insect is often seen as bothersome, disgusting, and easily squashed. While some people may see value in insects (for pollination, for example), most find them easy to ignore or horrific.
Because when you think of the most disgusting, hated insects... a cockroach is one of the first ones that comes to mind. Kafka wanted you to know exactly how he felt... hated, alone, disgusting.
Answer: Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment. Animals exchange heat with their environment through radiation, conduction—sometimes aided by convection—and evaporation.