Controlling Mosquitoes

The University of Georgia College of Agricultural & Environmental Sciences Cooperative Extension Service

Controlling Mosquitoes Around Our Homes and Neighborhoods

Revised and updated by Elmer Gray and Ray Noblet
University of Georgia Cooperative Extension Service and Department of Entomology

Mosquitoes can be a vexing and oftentimes serious problem. In homes, yards, and neighborhoods, mosquitoes can interfere with chores and spoil enjoyment of leisure activities. Some mosquitoes also transmit disease causing agents such as the protozoa that causes malaria and various types of viruses that cause disease in humans and horses, including West Nile virus and the new concern, Zika virus.

Biting and Flight Habits

Both male and female mosquitoes feed on plant nectar to provide energy for flight. However, only females seek blood meals to acquire the nutrients needed to produce eggs. During blood feeding, females inject saliva to keep the blood from coagulating and aid ingestion. It is this saliva that causes the irritation and welt that is associated with mosquito bites. Most female mosquitoes seek a blood meal at dawn and dusk, but there are exceptions. The yellow fever mosquito, Aedes aegypti, and the Asian tiger mosquito, Aedes albopictus, will bite during the day, more commonly in shaded areas. Both of these species develop in artificial containers, and are especially attracted to standing water in tires, rain barrels and buckets. The Asian tiger mosquito was first found in Georgia in 1994, and is now a common pest in every county in the state. This species has become a much more serious nuisance than the yellow fever mosquito that developed in similar locations and has similar habits.

Most mosquitoes can easily fly 0.5-1.5 miles from their larval habitat to seek a blood meal. However, there is a considerable amount of variation in this area of mosquito biology. Salt marsh mosquitoes may fly 25-35 miles from their larval site, while aegypti and albopictus fly only a few hundred feet.

Disease

Mosquitoes can function as vectors for a variety of disease causing agents. Vectors pick up a disease agent from one host and carry it to another. Today’s concern about transmission of the Zika virus has raised awareness of this fact around the world. The Zika virus is primarily transmitted by the Aedes mosquitoes, with Aedes aegypti being the primary vector across the Caribbean basin and Central and South America. Georgia only has a remnant population of this species. Aedes albopictus has transmitted the Zika virus in some locations and is a potential vector in Georgia. Symptoms associated with the Zika virus include flu-like symptoms including headache, a progressive-itchy rash, fever and muscle and back pain. Many patients also report photophobia and conjunctivitis (red eyes), however, 80% of the people exposed to the virus show no symptoms. A significant concern about the Zika virus is the birth defect microcephaly in newborns. Sexual transmission from men to their partners has also been documented. Information related to the Zika virus is regularly being updated and should be monitored on the CDC and Georgia Department of Public Health websites.

There are several other viruses transmitted by mosquitoes in Georgia that can cause encephalitis (inflammation of the brain). The elderly, individuals with compromised immune systems, and children are usually the most susceptible. The most common types of encephalitis in Georgia are West Nile, LaCrosse  and Eastern equine. Fortunately, transmission of viruses that cause encephalitis is rare in Georgia. Like encephalitis, yellow fever, dengue, and malaria were once common diseases in Georgia. However, they have long been absent. The mosquitoes that carried these diseases are still present, but in the absence of the disease agent and our general standard of living, cases of these diseases are limited to travel related occurrences.

Control

Because some mosquitoes can fly long distances, many communities in Georgia have organized mosquito control programs to provide area wide control. Support of your local program, if you have one, is your best option in preventing mosquito borne illness. Recent publicity about the Zika virus has renewed interest in mosquito control throughout the state. Integrated control programs operated at the community level will provide the most effective and efficient levels of mosquito suppression. However, in recent years many pest control operators have begun offering mosquito control services for individual home owners. These services can be effective, but should be based on Integrated Pest Management principles to assure effective and environmentally sound practices.

Many mosquito problems are caused by mosquitoes that develop in our own yards. If black and white-striped mosquitoes are biting during the day, you probably have the Asian tiger mosquito. As they don’t fly very far from their larval habitat, you could be raising them in your own yard. Below are methods you and your neighbors can use to reduce mosquito populations in your community:

• Remove old tires or drill holes in those used for playground equipment to allow them to drain. Tires are common larval habitats for several mosquitoes that bite humans and should not be stored outdoors.
• Check boats for holding water, clear drain holes, turn over, cover or increase angle to aid drainage.
• Check tarps on boats or other equipment/items that may collect water in pockets or indentations.
• Remove vegetation or obstructions in drainage ditches that prevent the flow of water.
• Pick up broken, unused or discarded toys that hold water.
• Pick up all beverage containers and cups.
• Replace water in birdbaths once a week.
• Replace water in pet and other animal feeding dishes or troughs at least once a week.
• Fill tree holes (hardwood trees) that hold water with spray, insulating foam sealant.
• Position garbage cans and lids so they don’t hold water.
• Change water in planters, including hanging plants, at least once a week.
• Maintain gutters so water drains properly.
• Monitor all types of drainage pipes/systems for standing water.
• Fix dripping outdoor faucets that create pools of water.

You can avoid or repel mosquitoes by the following:

• Keep door and window screens in good repair.
• Screen doors should open outward and have automatic closing devices and latches to prevent them from being accidentally left ajar.
• Wear protective clothing, loose fitting, long pants, long-sleeve shirts, shoes and socks during times and in locations of high mosquito incidence. Mosquitoes are less attracted to light clothing than dark. Be aware, mosquitoes can bite through T-shirts and other lightweight, tight-fitting clothing.
• During periods of excessively high mosquito incidence, stay indoors as much as possible.
• Use an EPA approved (DEET, IR3535, Picaridin, Oil of Lemon Eucalyptus) insect repellent before going into high-risk areas or when outside during high-risk periods (dawn and dusk) when mosquitoes are present. Follow the directions carefully. Mosquitoes will bite unprotected areas, so complete coverage is imperative. Don’t allow repellent to get in your eyes, mouth, or nose. The American Academy of Pediatrics recommends the use of repellents containing 30% or less of DEET on children 2 months or older. Children should NOT be allowed to apply repellents to themselves. Repellents should be applied to an adult’s hands and then applied to the child. The repellent should not be applied to the child’s hands and the treated areas should be washed after leaving the mosquito infested area.
• Permethrin based repellents can be used on clothing only. For maximum protection use an approved repellent on the skin and permethrin on clothing.
• Citronella based products are effective in repelling mosquitoes in protected areas of minimal air flow.
• Repellent lanterns and personal devices using a heat source and a repellent treated pad or wick have been demonstrated to be highly effective at repelling mosquitoes from small areas
• Do not rely on electronic bug killers or ultrasonic (sound) repellents for protection. They have not been scientifically proven to be effective.
• Mosquitoes don’t like strong wind currents. Sitting by a fan will repel them.
• Call the environmental health unit of your county health department to find out if there is a mosquito abatement program (spraying) in your area. If not, extra care in following these recommendations may be warranted.

There are a variety of methods to suppress mosquitoe populations:

• The first step is to eliminate all sources of standing water.
• Fish are highly effective predators and will control mosquitoes in most sites where fish occur.
• Larval habitats that cannot be eliminated should be treated with an EPA approved larvicide if mosquito larvae are present. Products with the biological control agent Bacillus thuringiensis var. israelensis are safe and effective and available at local home and garden stores.
• Pyrethrin aerosols will kill mosquitoes in the house.
• Hand held fogging devices using a pyrethroid based insecticide can be purchased from hardware and garden shops to give temporary control outdoors.  Be sure to buy the insecticide that is recommended with the device.
• Residual insecticides (bifenthrin, permethrin, cypermethrin) can be applied to areas where mosquitoes rest during the heat of the day. Sites may include shrubbery, ground covers and underbrush. 
  

A Problem

If your community has an organized mosquito program, it can be effective in greatly reducing mosquitoes that bite in the evening. These are usually controlled by applying ultra-low volume (ULV) sprays in the evening that drift through the area killing flying evening mosquitoes. The day biting Asian tiger mosquito and yellow fever mosquito are resting in the foliage and other protected areas in the evening and are not as susceptible to the spray as mosquitoes that are active during this period. If the ULV application is conducted during the day for these mosquitoes, rising air currents from the heat of the sun will cause the spray to go upward and be ineffective, rather than drift low to the ground as it does in the evening. The day biting mosquitoes can only be targeted with ULV sprays during the first and last hour of daylight when conditions are typically conducive for effective applications.

Since conventional adult spraying is difficult to conduct  effectively to control the daytime biters, eliminating their larval habitats is the best option. Unfortunately, government mosquito programs are not likely to enter private property to treat containers. This means you will need to control these mosquitoes yourself.

Remember, the day biters don’t typically fly far (100-300 yards) from their larval habitats. If you or your neighbors remove, cover or empty containers that contain standing water, you can greatly reduce your problem. You should not have expectations that a city or county mosquito program will be able to control these day biters for you.

Summary

With each spring, public awareness is renewed of the threat from mosquitoes and mosquito-borne diseases. In the years past, the greatest importance mosquitoes had in Georgia was the discomfort from their biting. Unfortunately, this is not the case anymore. The introduction of the West Nile virus and the potential threat posed by the Zika virus have increased the public’s awareness about the serious nature of mosquito populations. By eliminating the larval habitats on your property and taking a few simple precautions, you can reduce the threat of mosquito-borne illness and annoyance in and around your home and neighborhood.

Revised and updated by Elmer Gray and Ray Noblet, University of Georgia, Cooperative Extension Service and Department of Entomology. May 31, 2016.