Cobb County Extension Service
MOSQUITOES
Rain, though maybe not enough to provide a significant amount for your landscape, may be quite adequate for the mosquitoes. If you haven't been bitten by a mosquito yet, just wait. If there is some standing water, however little, it may be enough for the mosquitoes to start breeding. There are about 50 species of mosquitoes in Georgia. Lucky for us, they don't all bite humans. Enough do so that they can become a nuisance. It is only the female mosquito that bites, she needs blood to make eggs. The males feed mainly on nectar.
Different species of mosquitoes are active at different times of the day. Some prefer the early morning, some the evening and some during the day. Most are not active in the heat of the day or when there is a strong wind. At those times, they can be found resting in vegetation where it is cooler and the humidity is higher. Some species of mosquitoes can fly a mile or more but most of the mosquitoes that bite us in the inland areas of Georgia fly only a few hundred feet.
Why do they bite me more than other people? Sometimes it's a matter of where you are and when. The body chemicals of some people are more attractive to mosquitoes than others. The carbon dioxide we exhale, as well as some given off through the skin, acts as an attractant. Body heat, dark colored clothing and some fragrances also act as attractants. This area is being researched to find a suitable method of protection by using these natural body chemicals as repellents against mosquito. The body gives off hundreds of other chemicals that, in the proper combination, may keep the little beasties away.
Why does the bite itch? When the female mosquito bites she injects some saliva into the bite. The chemicals contained in the saliva keep the blood flowing through her needle-like mouthparts. It is also these same chemicals that our bodies react to, giving rise to the itchy bump or "mosquito bite". Like allergies, everybody reacts differently to the mosquito saliva.
In warm weather a mosquito can go through its whole life cycle from egg to adult in 7 days. The adult female lays her eggs in or near water or where water can expect to occur. The egg hatches into a larva. The developing mosquito larvae (or wrigglers) need very little water and feed on organic matter in the water. The larvae come to the surface of the water to breathe through a tube on the end of the abdomen, called a siphon. After a few days, the larva turns into a non-feeding stage - the pupa (tumblers). The pupa is not as active but must still come to the surface of the water to breathe through "trumpets", organs on the top of its back. The adult develops inside the pupa. After a day or two the pupa rests at the surface of the water, the skin splits open and the new adult eases out. Still or stagnant water less than an inch deep to many feet deep will support mosquito growth. They can breed in: bird baths, empty cans or plastic drink bottles, tires, tree holes (where a branch has broken off creating a small cavity), saucers under potted plants, blocked drains and gutters, pools of water around a malfunctioning spray head in a lawn irrigation system and any other place that will hold water for a week or more. Mosquitoes don't generally breed in water that is moving. They may be found among weeds or grasses growing in the water along the edges of streams.
There are a number of diseases that can be transmitted by different species of mosquitoes. Most of these can be treated with proper medical care. One disease transmitted by mosquitoes that used to be a major problem in the southeastern United States is malaria. That disease threat has essentially been eliminated through major water control projects and removal of the disease organism. Cases of malaria that occur in the area now are generally contracted through travel to another country where malaria remains a problem. Heartworm in cats and dogs is transmitted by mosquitoes from infected animals to unprotected cats and dogs. Some old information to the contrary, heartworm can be found in all areas of the U.S. and all pets allowed outside should be seen by veterinarians and be on medication to prevent this deadly disease. Heartworm does not cause a problem for humans. Other diseases spread by mosquitoes include Yellow Fever, viral encephalitis (Eastern Equine Encephalitis, St Louis Encephalitis, West Nile Virus and some others) and Dengue (breakbone fever - from the associated pain). Few cases occur and proper medical treatment generally takes care of the problem. To spread these diseases the female mosquito must first pick up the organism by feeding on a sick person. The organism must then undergo further development inside the mosquito before it can be passed on to a healthy person at another feeding many days later. No disease has been shown to be able to be transmitted by mosquitoes from one person to the next by the mosquito first biting one person and then immediately going to another for a second bite. For successful transmission to occur, the organism must undergo the development inside the mosquito and most disease organisms are incapable of doing that. Additionally, the adult female must live long enough after picking up the organism to allow for the development and then pass it on in a later feeding. Adult mosquitoes in nature often don't survive long enough, whether eaten by birds, frogs, dragonflies, etc, dying from weather or other unfavorable conditions. AIDS has NOT been transmitted by mosquitoes. It does not survive on the mouthparts or develop inside the mosquito. Various organizations within the state are monitoring the bird population to detect if any migrating birds might bring the disease into the area. The medical community will provide an alert if a problem should occur.
We like to blame the pond or swamp down the street or some nearby body of water or a neighbor's property as the source of the mosquitoes. Some mosquitoes can fly a couple miles or be blown by the wind, but that is generally not what happens. In most cases, the mosquito that bites you grew up within 100 feet of where you were bitten. That probably means it was in your own yard. So, where do you find them? Look for any type of container that can hold water. That includes flower pots and saucers, gutters stopped up by leaves, tire swings, cans, buckets, leaky sprinklers, toys and bottle caps can hold enough water for mosquitoes to develop.
To avoid being bitten try to avoid being outside when they are most active. The real problem biters are out around dusk and dawn. If possible, wear long clothing (not always practical in the heat of summer) and clothing of lighter colors. Go easy on or avoid using colognes or perfumes.
If you must be outdoors when mosquitoes are active, use a repellent applied to exposed skin to reduce the likelihood of being bitten. Try the repellent on a small area of skin before applying all over to make sure you're not sensitive to it. Follow the label directions. For young children be sure to use a formulation designed for children and not the adult strength.
Actions to take to reduce mosquito problems:
The best control is to make sure that any containers with water are emptied at least once a week. Fish and frogs in the ponds, including ornamental water gardens, and streams do a good job of controlling most mosquitoes that might try to breed there. Contact your local Cooperative Extension office for current recommendations for mosquito control.
Alternative Controls:
Biological control can be achieved by using fish in ponds and containers. The bacteria, Bacillus thuringiensis Berliner var. israelensis, is available to put in water to control larval development. This bacterial organism is specific for controlling mosquitoes and is safe for the environment. Oil of citronella is another compound used as an area repellent, usually in candles. It works in a limited area and only if there is no wind.
Electronic repellers/bug zappers do not provide mosquito control. Bug zappers kill as many beneficial insects as bad ones and most of those are drawn into your yard by the bug zapper.
Citrosa plants, while they contain an oil that may be repellent to mosquitoes, the plant needs to be crushed before the oils are released. Can you imagine a mosquito jumping up and down on a leaf hard enough to release the oils?
Insectivorous bats/purple martins - both are known to feed on mosquitoes. However, mosquitoes are only a small portion of their diet. They do help to reduce the population but they eat good bugs as well as the bad.
Many communities do not have an organized mosquito control program for a number of good reasons. Spray programs that utilize ultra low volume (ULV) sprays from planes or vehicles can help reduce the number of mosquitoes that bite in the evening. The spray drifts through the area and knocks down some of the active mosquitoes. ULV sprays can only be applied in early morning or late evening when there is no convective heat activity that would cause the pesticide to rise into the air and be ineffective or when there are breezes over 5 MPH. These applications would have almost no effect on the day biting mosquitoes (the ones that bite us the most) which are resting on or under plants at the time of spraying. Another drawback is the potential hazard of these vehicles driving through neighborhoods where children are playing as well as the potential health threat caused by widespread application of the pesticide chemicals. Communities have decided that the hazards associated with widespread application of chemicals and the resistance to the use of poisonous chemicals by a large portion of the local population far exceed the discomfort from mosquito bites.
Plymouth Mosquito Control Project, Massachusetts, an excellent informational web site with some great photos, just click on the buttons, http://www.plymouthmosquito.com/
Controlling Mosquitoes Around the Home, Rutgers University, http://www-rci.rutgers.edu/~insects/house.htm
FAQ's on Mosquitoes, http://www-rci.rutgers.edu/~insects/mosfaq.htm
Mosquito Information, American Mosquito Control Association, http://www.mosquito.org/mosquito.html
Mosquito Pest Management, Bulletin 641, Ohio State, http://www.ag.ohio-state.edu/~ohioline/b641/index.html
Mosquitoes: How to Control Them, US EPA, http://www.epa.gov/opp00001/citizens/mosquito.htm
Centers for Disease Control and Prevention, www.cdc.gov
The 1999 Introduction of the West Nile Virus to North America, University of Florida, http://www.ifas.ufl.edu/~veroweb/online/WNile/WNilemain3.htm.
For more information call Cobb County Extension Service, 770-528-4070 for the Mosquito Control pamphlet.
Article written By Jack Arnott 6/10/02
The University of Georgia and Ft. Valley State University, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.
