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More than just annoying insects, some mosquitoes are responsible for transmitting diseases that can result in serious illness and even death. Mosquitoes were once viewed merely as a nuisance because of the itching and irritation that resulted from their bites. In the early 1900s, however, they were recognized as carriers of yellow fever, malaria, and other diseases.
Not all species of mosquitoes suck blood. However in some species a blood meal by the female is essential to the reproductive cycle. In most species the females, like the males, suck nectar and other juices from plants for nourishment. The bloodsucking species feed primarily on mammals or birds, though some mosquitoes will feed on reptiles and amphibians. Some species are particular in their choice of host species, whereas others appear to be less selective. The feeding periods of many types of mosquitoes are restricted to particular times of the day or night. To obtain a blood meal, a female mosquito selects a likely spot on her victim, brings her labium against it, and begins sawing through the skin with her mandibles and maxillae. Through her hypopharynx she injects saliva into the wound to prevent the blood from clotting so that it flows freely into her labro-hypopharyngeal tube. She then sucks up a supply of blood, stores it in her abdomen, and flies away. The itching of a mosquito bite is caused primarily by the saliva that has been injected. If the mosquito completes her withdrawal of blood before being driven away, much of the saliva will be removed and the itching may be less severe.
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Watch a blood meal in action. |
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Mosquitoes are found almost everywhere in the world except open ocean areas, the most arid deserts, and the polar regions. Because of their dependence on water for development during their first stages of life, mosquitoes are most abundant in wet regions of the world. Nevertheless, of the more than 150 species of mosquitoes that inhabit the United States, many persist in arid regions of the Southwest. Some species thrive in the extremely cold climates of Canada and Alaska, where vast swarms can sometimes be seen around some of the larger lakes and marshes. Mosquitoes live in a wide variety of aquatic habitats. Besides lakes, ponds, and marshes, some mosquitoes lay their eggs in small depressions where water has collected temporarily. For example, many species use tree holes or fallen leaves, where water has accumulated after rains. In urban areas, common egg-laying sites for mosquitoes are empty containers that have collected water. Furthermore, mosquitoes are not restricted to fresh water for egg laying salt marshes are also a common habitat of many species.
Mosquito populations are reduced in two ways. Larval and pupal stages are controlled by treating standing water or by pre-treatment of areas where water will be contained after rainfall or flooding. Specialized equipment which produces an aerosol spray is used to control adult mosquitoes. The spray or "fog" is usually applied in the late evening or early morning hours when mosquitoes are most active. Only products labeled for this use and approved by the EPA are used in control programs. |
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