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July 2011

Mosquitoes can be controlled
Although a Constant Nuisance during the Summer Months, Mosquitoes can be Brought under Control

One of the most common pest problems homeowners face every summer are mosquitoes, a subject The Extension Office receives many calls about every year. The insects can breed prolifically. They inflict a painful bite and cause recreational areas, as well as the homeowner’s backyards, to be unusable. Worse, mosquitoes transmit some serious diseases, like Malaria and Yellow fever, although here in Gwinnett County, the main concern is West Nile Virus. They also can transmit diseases to household pets and livestock.
Mosquitoes require a source of standing or stagnant water to breed. They lay their eggs in the water, the insect larvae hatch and develop. You can often visually observe the larvae in the water as they appear as “tumblers”, small worm like organisms, roughly a quarter to one half of an inch long wiggling around. In time, they mature as adults and leave the water. The male mosquitoes do not bite. They feed on plant material and nectar. The females require a blood meal before they begin egg production. They are most active at dawn and dusk, and hide in shrubbery and other vegetation during the day.
One of the best ways to control mosquitoes is source reduction, which requires seeking out and eliminating sources where they breed. Look over your property and see if there are any sources of standing water and remove unneeded containers such as old tires. A common source of mosquitoes is gutters that are clogged and need to be cleaned out. Empty pet dishes, bird baths and saucers under potted plants every 4 to 7 days. Cover or turn upside down boats, wagons, wheel barrows, toys and other things that catch water. Get rid of old drink cans, plastic cups and other containers. It takes only four inches of water to raise mosquitoes.
Often you have sources of water that can not be removed such as ponds and garden pools. The mosquito larvae can be controlled by a small, minnow like fish called a Gambusia. Keep the pond weeds to a minimum so the fish can find the larvae to feed on.
Another method of control is using products such as Mosquito Dunks, which are a bacterial biological control agent that specifically targets mosquito larvae but does not harm other organisms. The Mosquito Dunks slowly dissolve over a period of thirty days, and periodically have to be replaced. Other options include treating the water with methoprene, an insect growth regulator that disrupts their growth cycle. Some chemicals, such as Agnique, produce a film over the water smothering the mosquito larvae. Burning mosquito coils can give relief from the insects, but only in the immediate area.
When it comes to using chemical control, it should always be used in conjunction with source reduction. Mosquitoes inside the house can be controlled with aerosol sprays. Outdoors, they sometimes can be brought under control by insecticide sprays applied by foggers. Residual insecticides (malathion, permethrin) can be applied to shrubbery, ground covers and underbrush, and other places where mosquitoes rest during the heat of the day. This action will help reduce, but not totally eliminate the mosquitoes.
If you are planning to be outdoors for any length of time, apply insect repellants containing a mosquito repelling chemical called DEET. It comes in concentrations ranging from 10% to 35%. Use the smaller concentration on children, and reserve the higher concentration levels for adults. The repellants are effective for temporary control of mosquitoes. When using any chemical, please follow all label directions and safety precautions.
Citronella candles are relatively ineffective, unless you are standing right next to them. Bug zappers are usually not effective in controlling mosquitoes. The insects that are caught in the bug zappers usually are not mosquitoes and are often beneficial insects.
And you can forget about those ultrasonic devices for sale to control mosquitoes. They are ineffective and are just a waste of money.
Despite mosquitoes being a major irritation and a source for diseases, they can be controlled and their harmful activity minimized. For any questions regarding mosquito control, please contact the Gwinnett County Extension office.

Timothy Daly, is an Agricultural and Natural Resource Agent with Gwinnett County Extension. He can be contacted at 678-377-4010 or

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