What are mosquitoes?
Mosquitoes are small, long-legged, two winged insects belonging to the order Diaptera ( meaning two winged ) and the family Culicidae. The adults differ from other flies in having both an elongated proboscis and scales on the wing veins and wing margin. This is a very large group, containing over 2,600 species. There are about 162 species in the United States belonging to 13 genera in three subfamilies.
The most important mosquitoes to us in Rhode Island and Massachusetts are Genus Anophelinae, genus Aedes, Mansonia, Culex Culiseta, and Psorophora due to the fact they serve as vectors of diseases like malaria, yellow fever, dengue, filariasis and various forms of encephalitis.
Mosquito Life Stages
Mosquitoes have 4 distinct stages in their life ; egg, larva, pupa, and adult. The first three stages take place in water ( eggs may also be laid in soil ), but the adult is an active flying insect , feeding on the blood of vertebrates and on plant juices.
In our effort to control mosquitoes population we focus on eggs, larva and adults, therefore, here is a brief description of these life stages.
The behavior of the female determines where the eggs are laid and this behavior is quite constant for a given species. Eggs are white when firsts deposited , becoming dark within an hour or two. In general, mosquito eggs fall into three distinct groups: (1) those that are laid as a single egg on the water surface, (2) those that are glued together to form rafts which float on the water surface or are glued to the objects in the water, and (3) those that are laid as single eggs out of the water.
The larva of all mosquitoes live in a non-flowing water. Some species live in permanent ponds and marshes, some in water contained in tree holes or leaves of plants, and others in artificial containers. Some species of mosquitoes adapted themselves to almost all kinds of aquatic situations except the open waters of large flowing streams, lakes, and seas. Although mosquito larva get their food from water in which they live, they must come out to the surface for airor, as in the case of Mansonia, obtain air from the underwater portions of plants.
As pointed out, females lay their eggs in quite specific places, thus it follows that larva develop in typical habitats. If one knows the available types of larval habitats in an area, one can often predict the species that will occur there, or in reverse, if one has biting records of species causing trouble, it is possible to predict the types of habitat. It is possible to classify larval habitats and several general types in Rhode Island and Massachusetts are: (1) temporary snow melt, rain and tide water pools, (2)
temporary flood pools caused by overflow from streams, (3) permanent or semi-permanent ponds and swamps, (4) natural containers such as plant leaf axils, rot cavities in trees and rock pools, (5) artificial containers such as tin cans, automobile tires, animal food containers, and all kinds of storm water catch basins , and (6) attached to roots of aquatic plants, such as cattails.
The larval period which includes four developmental instars , usually requires a minimum of 4 to 10 days for completion. At the end of each instar the larva molts ( sheds its skin ). the fourth instar is the mature larva and with the fourth molt the pupa appears.
The adult mosquito is a small fragile insect with a slender abdomen, one pair of narrow wings, three pairs of long, slender legs and a proboscis. The adult varies in length from slightly over 1/16 inch to about 1/2 inch. The ratio of male to female mosquito is usually 1:1. Males emerge first and remain closer to the breeding places. Females tend to travel greater distances and live longer than males. The range of flight depends on weather conditions, especially wind, and species involved. When Culex Pipiens or Aedes Triseratus are the pest of source the flight range is short and typically few hundred feet from the source. When Aedes Vexan or Aedes Sollicitans is the pest, the larval habitat might be several miles away.
Adult Mosquito Feeding Habits
The primary source of energy for both sexes is nectar. Males do not suck blood. Females of most species require a blood meal in order to obtain protein needed to produce an egg. It is important to note that not all species of mosquitoes feed on people. Most species will feed on wide range of both birds and mammals but due to various ecological and behavioral characteristics are often associated with 2 or 3 major hosts in a given area. In general the feeding patterns of mosquitoes can be broadly grouped in 4 categories; those that feed mainly on mammals, those that feed mainly on birds, those that feed on cold blooded vertebrates , and general feeders tat attack a wide variety of hosts. Most species are categorized in the first group and most arbovirus ( A class of viruses transmitted to humans by arthropods such as mosquitoes ) to man are of the general feeders type.
Mosquitoes Activity Patterns
Most northern species are active mainly during and just after dusk and for a short while before dawn. However, several species ( mainly Aedes ) will bite during daylight hours in subdued light in homes or in shade. Few species will bite even in full sunlight if their habitat is invaded. Culiseta , Mansonia, Anopheles and Culex are generally more active in the later part of twilight period and after dark.
Mosquitoes spend most of their life resting in places with subdued light , where there is little or no wind. Thus, during the day hehy will hide near dump soil in grass, dense shrubbery or woods.. Barns, sheds, garages , cellars, culverts, rock ledges and forest litter are excellent resting places. Still, a few species (e.g. Aedes Sollicitans rest in low vegetation in open windy ares such as salt marshes.