proboscis brackish

Background

Photo: Golden Saltmarsh Mosquito photo courtesy of SandSeekers.net

The saltmarsh mosquito, Aedes solicitans, can be found, along with its relative, the black saltmarsh mosquito (Aedes taeniorhynchus) along the Atlantic Coast, and proliferates in and around the brackish waters of the Chesapeake Bay.

Mosquitoes belong to the Culicidae family in the order Diptera, which contains more than 86,000 species of flies. The mosquito appears slender and delicate, with a visibly sharp proboscis that distinguishes it from other members of the fly order. Males tend to have feathery antennae. Both sexes have delicate scales on wings. Mosquito larvae can be ¾ inch long, and the pupae grow up to ¼ inch. The larvae live in still ponds and puddles, leaves of plants, stagnant ponds or lakes.

The mosquito has influenced human history perhaps more than any other single family of insects, by transmitting diseases such as yellow fever and malaria, forms of encephalitis, and West Nile virus, among others. This insect is considered the most efficient and powerful transmitter of disease in the animal kingdom.

About 3,000 species of mosquitoes exist throughout the world, and about 150 occur in North America. This group requires blood for the formation of eggs; thus it is the females, not males, that bite. For every batch of eggs she lays, a female mosquito requires a blood meal, but at all other times, both males and females subsist on sugar-based foods, such as plant nectar or fruit juices from plants.

When the female bites she injects saliva into the site, which prevents blood from clotting before she can withdraw it. The saliva causes an allergic reaction in many people, leaving a welt, which if possible should not be scratched, since bacteria from the fingernails can be introduced into the wound and cause infection.

Scientists are puzzled by why some people attract mosquitoes more than others do. They do know that females follow the slipstream of exhaled CO2 to a human host, then navigate using different cues once they've reached close range. It's believed that dark clothes attract mosquitoes more than light and that the scent of soaps, perfume or hairsprays can mask the scent of other chemicals released through human skin, such as folic acid, which tends to attract mosquitoes.

The process by which mosquitoes transmit disease begins when a female consumes blood from one host, which may contain the blood stage of a human parasite. This parasite may multiply or complete another phase of its life cycle while inside the mosquito, while she is laying her eggs. After she has laid her eggs, she seeks another blood meal, transmitting the fully developed parasites into the next host.

The mosquito can transmit several commonly known, potentially dangerous diseases:

• Yellow fever is a viral infection that can be transmitted between monkeys and humans or vice versa, in tropical climates. · Encephalitis is a viral disease that attacks the central nervous system and is often transmitted from birds to humans by mosquitoes that consume the blood of each.
• Malaria is a protozoan parasite that infects human blood cells and is transmitted among humans by Anopheles mosquitoes.
• West Nile virus is commonly found in Africa, West Asia and the Middle East, and is found in humans, birds and other vertebrates in those areas; it was not documented in the Western Hemisphere until 1999. It causes West Nile encephalitis, a dangerous infection of the brain. The strain that has been found in the U.S. is most closely genetically related to strains found in the Middle East, according to the CDC. Mosquitoes are infected with the disease when they feed on infected birds, then transmit the virus, which is located in the mosquito's salivary glands, into humans while biting. Even in areas where mosquitoes carry the virus, less than 1 percent are thought to be infected, and fewer than 1 percent of those infected by bitten by a mosquito will become severely ill.

Aedes solicitans usually grow to 1/8 of an inch to ¼ inch, and are golden brown. The male is unmarked. The female's abdomen shows a silvery stripe and silver or golden-yellow bands. The female's proboscis has white and black bands. The male's antennae are feathery and the female's are threadlike. The wings of both are smoky, and the females' are spotted.

This species occurs near brackish and salt water, and its larvae can survive in swimming pools. Its range extends from Maine to Florida, as far west as Texas and north to Nebraska. Like other mosquito species, males feed on plant juices, while females suck blood from wild and domestic animals and humans. Larvae eat algae and single-celled animals. Females lay eggs singly or in batches on vegetation or other surfaces at the waterline. The larvae then hatch and pupate in stagnant water.

The black saltmarsh mosquito, A. taeniorhynchus, is black with broad white bands, shows different patterns on its proboscis and has no mid-dorsal stripe. This species is found in Massachusetts, south along Atlantic coast, west along Gulf of Mexico, into southern California.

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Last modified: 7/01/02