Mosquitoes

Mosquitoes have four stages in their life cycle beginning with the egg, then proceeding into a larva stage, followed by a pupa stage, and finally adulthood. Female mosquitoes deposit their eggs in a number of different environments depending on the particular species. While the larvae can only live in water, eggs are not always laid in water. Some species deposit their eggs in areas that may not be flooded for a number of years, but the eggs can survive for several years until the next flood. Other species deposit them separately on top of the water and others deposit them in groups on the water's surface. These are called "rafts." When the eggs are first laid they are white in color, but they change to black or brown in a short time. Some mosquito eggs, such as the Anopheles, have a hull-like shape with extensions on either side, giving them the appearance of tiny rafts. Some mosquito eggs are able to trap air bubbles. From 30-500 eggs are laid at one time by females, depending on the species. Most hatch in two or three days into aquatic larva.

During the larva stage, they feed on plankton and move by wiggling, hence the name "wiggler," which is applied to mosquito larvae. The larva life span varies, again depending on the species. Some develop rapidly within days, while others may take months to develop. They also exhibit a variety of feeding habits, from scavenging dead food, bottom or surface feeding of plankton, to eating other living organisms. The next stage, the pupa, which occurs just before maturity, takes place on the surface of the water, where the pupa breaks out of the larva shell. The transformation from larva to pupa takes only several minutes and occurs at the surface of the water. The pupa stage lasts from two to three days in the tropics to several weeks in cold climates.

A mosquito withdraws its proboscis after feeding in Alpena, Michigan. Photograph by Rod Planck. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.

As adult mosquitoes leave the pupal stage they swallow air which helps them expand their abdomen and wings. Among the various species there are different ratios of male and female births. The life span of mature mosquitoes ranges from a few days to over a month depending on the species and the climate. Those living in hotter climates tend to have a shorter life span.