Spiracles are holes in body wall that let air into tracheal tubes. Excretion by Malpighian tubules receive metabolic waste from blood Concentrate waste and discharge waste into intestine. Conserve water Sexes separate, internal fertilization primitive, wingless insects like silverfish have direct, simple development. Pupa in cocoon doesn't feed, does change form to adult with functional wings and reproductive organs. Why bugs took over the world tough exoskeleton protects from predators, prevents evaporation of body fluid segmented exoskeleton allows mobility and flexibility Body plan is amazingly adapted to lifestyle.
Segmentation allows regional specialization.
Flight move freely because they're small and winged. Eggs have thick membrane and some packaged in egg case. Metamorphosis keeps life stages from competing directly with each other. Communicate with tactile, auditory, visual, chemical signals. Ants use pheromones to mark trails.