Reproduction In insects, reproduction is usually sexual, with separate male and female animals. Fertilization is usually internal. In most species, sperm are deposited directly into the female's vagina at the time of copulation, though in some species the male deposits a sperm packet outside the female, who then picks it up. The female reproductive system may also include a spermatheca, a blind sac in which sperm may be stored for a year or more. Though most insect species produce a multitude of eggs, some flies produce live offspring, usually a single young at a time.
Many insects mate only once in a lifetime.
The cuticle can be modified into a thick, hard armor over some parts of the body or be paper-thin and flexible in other locations, such as the joints of the appendages. The exoskeleton protects the animal and provides points of attachment for the muscles that move the appendages. To grow, an arthropod must occasionally shed its old exoskeleton and secrete a larger one, a process called molting. Many insects have one or two pairs of wings that attach to the dorsal side of the thorax. Since the wings are believed to have developed from basal parts of the legs rather than whole appendages, insects are able to fly without sacrificing any walking legs.