Description

The Asian tiger mosquito (Aedes albopictus) is a small black and white mosquito, about 1/4-inch long. The name "tiger mosquito" comes from its white and black color pattern. It has a white stripe running down the center of its head and back with white bands on the legs. Note that other Illinois mosquitoes also have banded legs.

These mosquitoes lay their eggs in water-filled natural and artificial containers like cavities in trees and old tires; they do not lay their eggs in ditches or marshes. The Asian tiger mosquito usually does not fly more than about 1/2 mile from its breeding site.

Life Cycle and Habits

The wormlike mosquito larvae swim with a wriggling motion and are sometimes called “wrigglers.” About 10 days after hatching, the larvae are about 1/4-inch long and completely grown. They then change into comma-shaped pupae that are sometimes called "tumblers" because of their tumbling motion in water when disturbed. The pupa stage completes their development into adult mosquitoes. When fully developed, an adult mosquito will emerge from each pupa at the water surface. Adult mosquitoes emerge from pupae in as little as 10 to 14 days after the eggs hatch during the summer.

Asian tiger mosquitoes spend the winter in the egg stage, hatching into larvae when the eggs are covered with water in the spring and summer. The larvae feed on small bits of debris and bacteria in the water.

Male mosquitoes feed on plant juices and do not bite. Female mosquitoes seek blood to help their eggs develop. Unlike many other Illinois mosquitoes, the Asian tiger feeds during daylight hours, not at night. As with other mosquitoes, though, Asian tiger mosquitoes are attracted to dark clothing, perspiration, carbon dioxide and certain other odors. The mosquito will bite squirrels, dogs, deer and other animals as well as people. About four or five days after feeding on blood, the female mosquito lays her eggs just above the surface of the water in a hard-sided container like a tree hole, old bucket or tire. When rain covers the eggs with water, the larvae hatch.

Importance

The Asian tiger mosquito was introduced into the United States. in tire casings imported for recapping. Movement of tire casings has spread the species to more than 20 states since 1985. The tiger mosquito is an important disease carrier in Asia. In the United States, it has been found to be infected with LaCrosse encephalitis viruses and West Nile virus, which can cause encephalitis (inflammation of the brain). However, it is presently unclear whether the Asian tiger mosquito will be a significant carrier of disease in the in the United States.

The bite of the Asian tiger mosquito is not particularly irritating to most people, but they are persistent biters. Because they breed in nearly any sort of water-filled container, they often become very common and bothersome, even in neighborhoods where there are normally few mosquitoes. In some southern cities, the Asian tiger mosquito has become the most important nuisance mosquito.

Prevention and Control

It is not necessary to limit outdoor activities unless there is evidence of mosquito-borne disease in your area. However, you can and should try to reduce the risk of being bitten by mosquitoes:

• Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
• Be sure door and window screens fit tightly and are in good repair.
• Wear shoes, socks, long pants and a long-sleeved shirt when outdoors for long periods of time, and when mosquitoes are most active. Clothing should be light colored and made of tightly woven materials to keep mosquitoes away from the skin.
• Use mosquito netting when sleeping outdoors or in an unscreened structure, and to protect infants when outdoors.
• When it is necessary to be outdoors, apply insect repellent as indicated on the product’s label. The more DEET a product contains, the longer the repellent can protect against bites. However, concentrations higher than 50 percent do not increase the length of protection. For most situations, 10 percent to 25 percent DEET is adequate. Apply to clothes when possible, and sparingly to exposed skin if the label permits. Consult a physician before using repellents on young children.
• Note that insect light traps ("bug zappers") or sound devices do little to reduce the number of biting mosquitoes in an area.
• Spraying your backyard with an insecticidal fog or mist is effective only for a short time. Mosquitoes will return when the spray dissipates.
• Installing bird or bat houses has been suggested as a method of mosquito control. However, there is little scientific evidence that these insect-eating animals significantly reduce mosquito populations around homes.

Because the Asian tiger mosquito is active during the day, "fogging" (space spraying from specially equipped trucks) provides little control, as this method is generally ineffective due to atmospheric conditions during daylight hours. You can, however, greatly reduce the number of tiger mosquitoes in your area by getting rid of breeding places:

• Remove any water-filled containers like old tires, food containers and buckets from your yard.
• Keep mosquitoes from breeding in bird baths, pet water dishes and plastic wading pools by emptying them at least once a week.
• Roof gutters should be kept clean of fallen leaves and other debris so that water does not collect in them.
• Neighborhood residents should work together to eliminate breeding sites like abandoned cars, old machinery, drums and other junk in vacant lots.
• Report piles of discarded tires or other accumulations of water-holding junk to local health officials.
• Businesses should cover tires, store them indoors or treat them with an insecticide labeled by the U.S. Environmental Protection Agency for control of mosquito larvae.

These measures will also help control other Illinois mosquitoes that are disease carriers.