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The adult mosquito is a fragile insect with a slender abdomen, one pair of narrow wings, three pairs of legs and a proboscis. The adult varies in length from 1/16 inch to 1/2 inch. The three body regions, head, thorax and abdomen are distinct.

The range of flight of the adult is a difficult problem to answer. Many factors are involved in this area. No clear statement can be made because the answer depends to a on large extent the species involved and the weather conditions, especially wind. When C. pipiens or Ae. triseriatus is the pest the source is usually close by, often within a few hundred feet.

When Ae. vexans or Ae. sollicitans are involved, the larval habitat may be several miles away from the point of annoyance.

The sex ratio in adult mosquitoes is usually 1:1. Males ordinarily emerge up to a day first. This is important, because the genitalia are reversed upon emergence, and requires up to 24 hours to rotate into the proper position for copulation. The male mosquito remains close to the breeding area to await the hatching of the females. Some females are receptive to mating soon after emergence, but others require 1 to 2 days to become ready. Males of most species congregate into small swarms, usually over an object such as a bush or tree limb. Females are audio attracted to these swarms and once they fly into the swarm are grasped by a male and copulate while falling or on the ground. Most species do not seek a blood meal until after mating has occurred. Sperm are stored in a specialized structure in the female, and she may lay several fertile egg batches following a single mating.

The primary source of energy for both sexes is nectar. Male mosquitoes do not seek blood. The females of most species require a blood meal in order to obtain protein needed to produce a batch of eggs. Some species have specific hosts. Culex territans and Uranotaenia sapphirina seek cold blooded hosts such as amphibians and reptiles. Some species, such as Wyeomyia smithii, develop eggs without taking a blood meal (autogenous). Some species may be partially autogenous; they may be able to produce a small first batch without a blood meal, but need blood to develop additional egg batches. Most species need from 4-8 days after a blood meal before the eggs are fully mature and ready for laying (oviposition). In some species, as soon as the eggs are deposited the female may feed again.

Most species will feed on a wide range of both birds and mammals but are often mainly associated with 2 or 3 major hosts in a given area. A few species appear to be restricted to specific hosts, and can be broadly grouped into four major types: those that feed on mammals (Anopheles, Aedes, Ochlerotatus, Psorophora and Coquillettidia), those that feed mainly on birds (Culiseta melanura, Culiseta morsitans and Culex restuans), those that feed on cold blooded vertebrates (Culex territans and Uranotaenia sapphirina) and general feeders that feed on a variety of hosts. Of special concern are the species that will seek out both birds and mammals, because they can be a vector of EEE (Eastern Equine Encephalitis), which is an arbovirus (virus of birds).

Some species have a single generation in a year, such as Oc. stimulans, Oc. abserratus and Oc. excrucians to name a few. The eggs of these species need to be cold conditioned. Others are able to have multiple generations in a year, Ae. vexans, Oc. sollicitans, Culex and Anophelene species are a few found in this area. Most northern species are mainly active during and just after dusk, and a short while before dawn. But several species (mainly Aedes & Ochlerotatus) will bite during daylight hours in subdued light in our homes, or in the shade. A few species, such as Oc. sollicitans will bite in bright sunlight if a host disturbs their resting habitat. Culiseta, Coquillettidia, Anopheles and Culex are generally more active in the later part of the twilight period and after dark than are Aedes, Ochlerotatus and Psorophora.

The greatest part of an adult mosquitoes lifetime is spent at rest. Most mosquitoes rest in moist places with subdued light, where there is little wind. One of the biggest concerns for the adult is loss of water from its tissues. This loss may become critical during the daytime when temperature is high and humidity low. During the daytime mosquitoes often hide near the damp soil in grass, in dense shrubbery or in the woods. Because of this behavior, many people assume mosquitoes breed in these areas, but these are only resting places for the adults. A few species, such as Oc. sollicitans, rest in low vegetation in open areas such as salt marshes.

For more information on adult mosquitoes and their control, please contact the CMMCP office at 508.393.3055 or through e-mail.