How do mosquitoes cause disease?

 The female mosquito needs the blood of a warm-blooded animal for the proper development of her eggs. To get this, she needs to bite such an animal.

 The mosquito can take in as much as twice its body weight in blood, thus giving it a relatively good chance of picking up infectious agents such as malarial parasites circulating within the host’s capillaries.

 The anatomy of a mosquito is particularly adapted to transmit disease . The mouthparts of the female mosquito consist of sharp stylets that are forced through the host’s skin to the subcutaneous capillaries. One of these needlelike stylets is hollow, and the mosquito’s saliva is pumped through it. 

The saliva increases blood flow and prevents clotting as the victim’s blood is sucked into a tube formed by the other mouthparts of the insect. The saliva can also cause allergic reactions (the itch of a mosquito bite). After the mosquito has taken more than one blood meal, she can transmit disease from one animal to the next. Viruses found in the blood of the first animal are then transmitted to the next, and so on.

Mosquitoes in an area of arthropod-borne disease can be trapped and identified microscopically, and the blood they have ingested can be tested to see on which kinds of animals the different species are feeding. Precise identification of species and subspecies of these genera is important because different species of mosquitoes differ greatly in their breeding areas, time of feeding, and choice of host.

 Identification depends largely on microscopic examination of antennae, wings, claws, mating apparatus, and other features. Correct identification is often essential in designing specific control measures.