Throughout the world, mosquitoes are one of the most serious pests of humans. They are capable of inflicting an irritating bite and making recreational areas unusable. A more serious problem arises when mosquitoes vector diseases to humans and domestic animals. In the U.S. these serious diseases include various types of encephalitis including West Nile virus, but in other parts of the world yellow fever, malaria, dengue and filariasis are common and often deadly.
During their life mosquitoes, go through four stages of development: egg, larva, pupa, and adult. The first three stages take place in water. The females usually require a blood meal before egg production. Most female mosquitoes lay batches of 50-200 eggs on or near water surfaces.
Ideal breeding places include temporary flood waters, edges of lakes and ponds, woodland pools, marshes, swamps, discarded tires, trash, tree stumps, knot holes, and bird baths. The eggs of most species hatch in two or three days. Some species require a drying period and may lie dormant for months.
Larvae feed mainly on bits of organic matter in the water, and most species must come to the surface for air. After about a week, the larvae pupate and are comma-shaped. Sometime they are called wrigglers because of the motion they make when the water is disturbed. The pupal stage, which is called a tumbler, lasts about two days. With such a short life cycle, the population can grow very quickly.
All adult mosquitoes can fly but only the female bites and feeds on the blood of humans and other animals. Females may live several weeks.
Mosquito populations can be controlled in two ways: source reduction and chemical control. Source reduction is the least expensive and most effective of the two methods. It requires finding and eliminating possible breeding places. Look for standing water and remove unneeded water containers such as tin cans, and old tires. If these things need to be saved, place them where water won’t collect in them. In ponds, garden pools and other areas that cannot be drained, mosquito larvae may sometimes be controlled by a type of bacteria called Bacillus thuringiensis israelensis (Bti). There are many products containing Bti for water treatment. Other non-chemical ways to reduce mosquitoes include:
- Tightly covering cisterns, cesspools, septic tanks, barrels and tubs of stored water;
- Emptying and washing birdbaths weekly;
- Cleaning out rain gutters;
- Examining flat roofs after rains to be sure no water remains on them;
- Draining or filling stagnant pools and swampy places;
- Removing debris and floating vegetation from areas that cannot be drained or filled;
- Eliminating standing water in saucers under potted plants;
- Examining trees for decayed places that hold water and then drilling drainage holes to remedy the situation
- Keeping screens on doors and windows in good repair.
Chemical control of mosquitoes should be used only as a supplement to source reduction. Outdoors, some adult mosquitoes can be controlled with misting sprays of insecticides directed to where adults rest on or very close to structures. Many insecticides are labeled for use by homeowners. Products can be purchased at hardware, grocery and discount stores. Before using any insecticide, always read the label and follow directions and all safety precautions.
Many communities, cities and counties participate in projects that coordinate area-wide mosquito management districts. Large area efforts are likely to be more successful in controlling mosquito populations than the efforts of a single property owner. For more information about mosquito area wide control programs, see the SC Department of Health and Environmental Control web site. To read more about using repellents for mosquitoes, see the US Center for Disease Control web site.