Mosquito Anatomy

Although there are almost 3,000 types of mosquitoes in the world, they all have basically the same anatomical features and biological development. For details about individual species, please refer to other articles on this web site.

Like many insects, mosquitoes go through four stages of development. The following are general descriptions of the biology and physical characteristics of most mosquitoes in these four stages.

Stages of Mosquito

Eggs

Mosquito egg-laying is always associated with a water environment. Some species lay their eggs directly into the water, while others lay eggs in damp soil or containers that will soon be flooded by rain. Whatever the location, water is necessary for the development of mosquitoes.

Eggs are typically laid one at a time and, in some species, these may form an egg “raft” that floats on the water’s surface. The egg’s appearance varies by species. Some are white, while others are brown or black. The eggs typically have an oblong shape.

If the female mosquito has fed on blood, the eggs are more robust and have a better chance of hatching. Most mosquito eggs hatch into the larval stage within 48 hours after being deposited. However, if laid late in the season, eggs of some species may over-winter and hatch the following spring. In fact, the eggs of some species can survive this way for years.

Larvae

Once the egg hatches, it becomes a tiny larva. The larva has no legs and its thorax is enlarged at this stage, appearing wider than its head and abdomen. Thus, the larvae have a worm-like appearance and wiggle about in the water. This manner of movement has led to the nickname of “wigglers” for this stage of development.

Larvae feed on algae or other organic matter in the water and come to the water’s surface to breathe. They feed by sweeping water with large fan-shaped bristles. In many species, breathing is conducted through a siphon as they hang upside down from the water’s surface.

Depending on the species, the larval stage may last for 7-10 days. The larvae develop through four to five molts (shedding the skin) and then pupate.

Pupae

The pupae do not feed, though they are often very active in the water. The pupae are lighter than the surrounding water, so they very readily float. They respond to light changes or disturbance of the water surface by flipping their tail and moving to the bottom of the water or to a protective area. The flipping movement has earned the pupae the nickname of “tumblers.”

After 1-3 days, the pupal skin splits and the adult mosquito emerges.

Adults

Upon emerging from the pupal stage, the body parts of the adult are quite soft. They soon harden, when they are dried by the warm air. Once the wings spread out and are sufficiently dry, the mosquito is ready to fly away.

Both male and female mosquitoes have globular heads with compound eyes. They have a pair of antennae that may measure up to three times the length of the head. These antennae are hairy in the female and have a bushy appearance in the male. Mosquitoes have a single pair of wings. The vibration of the wings is used in communication related to mating; males can locate females by following the high-pitched sound of the wings – even in the dark.

The mouthparts of a mosquito form a long, thin proboscis. This is used for feeding on nectar in both sexes and, in females, it is used for piercing skin and feeding on blood. The female’s proboscis is made up of six separate shafts. Four are cutting and piercing tools, one is for pumping the saliva into the wound, and the last one is for drawing blood from the host. Thus, the shaft that injects saliva (and disease) is not the same shaft that draws blood, which reduces the risk of mosquitoes directly transmitting most diseases directly between its victims.

The adults mate 24-48 hours after they emerge from the water. Details about mating may be found elsewhere on this web site.

General

Again, the above are general descriptions for most mosquitoes. Physical traits seen in each stage may vary by species. Moreover, each stage may vary in length, according to species and temperature. For example, in the right environment, some species of mosquito may go from egg to adult stage in 10 days. Others may take three times as long.

Once she has a blood meal, she will lay her first (and largest) brood of 50-500 eggs. Thereafter, her broods will be smaller, but she may have 8-10 broods and must feed on blood between each.

Males die after six or seven days in most species, whereas the female may live 2 weeks to 3 or 4 months during the summer. In some cases, a female that emerges from pupal stage late in the season may over-winter to survive cold temperatures.

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