Mosquitoes can carry debilitating and deadly diseases. Even those species who don't transmit disease to humans, pets or other animals can be an extreme nuisance, causing itchy bites.
Currently, there are no vaccines available to protect us against mosquito-borne diseases that occur in Virginia, and there are no specific treatments for West Nile virus encephalitis and other viral diseases spread by mosquitoes in Virginia. Because of this, prevention of mosquito bites is currently our best hope of protection against mosquito-borne disease.
Currently, there are no vaccines available to protect us against mosquito-borne diseases that occur in Virginia, and there are no specific treatments for West Nile virus encephalitis and other viral diseases spread by mosquitoes in Virginia. Because of this, prevention of mosquito bites is currently our best hope of protection against mosquito-borne disease.
Limit mosquito-breeding areas around your house
Most of the life cycle of a mosquito occurs in water. For many, the idea of a mosquito breeding area conjures up images of vast tropical swamps. In reality, many mosquito species breed only much smaller bodies of water. In natural areas, these so called container-breeding mosquitoes use tree holes, indentations in rocks, or even water pooled in fallen leaves. In urban and suburban areas, these mosquitoes will also use water collected in bird baths, clogged gutters, and anywhere else water can pool. A single tablespoon (15 mL) of water is sufficient to provide a breeding ground for some mosquitoes.
In Virginia, the mosquito of greatest concern in the Asian tiger mosquito, Aedes albopictus. This mosquito is responsible for the majority of bites in Virginia. In addition, the Asian tiger mosquito is a vector for West Nile virus, La Crosse encephalitis, and possibly eastern equine encephalitis. It is a strict container breeder. It won't breed in any container that has soil at the bottom, such as a pond, lake or drainage ditch. The most effective way to reduce the number of Asian tiger mosquitoes and other container-breeding mosquitoes is to reduce the number of breeding containers.
Where are the problem areas, and what can be done about them?
In Virginia, the mosquito of greatest concern in the Asian tiger mosquito, Aedes albopictus. This mosquito is responsible for the majority of bites in Virginia. In addition, the Asian tiger mosquito is a vector for West Nile virus, La Crosse encephalitis, and possibly eastern equine encephalitis. It is a strict container breeder. It won't breed in any container that has soil at the bottom, such as a pond, lake or drainage ditch. The most effective way to reduce the number of Asian tiger mosquitoes and other container-breeding mosquitoes is to reduce the number of breeding containers.
Where are the problem areas, and what can be done about them?
- Tree holes are a favorite breeding ground for many mosquitoes. In fact, the common name for the mosquito vector of easter equine encephalitis is the treehole mosquito (Culiseta melanura). Tree holes can be filled with sand or mortar to prevent breeding of mosquitoes.
- Toys in the yard, from a sandbox pail to a toy car to an overturned Frisbee can hold more than enough water to breed mosquitoes. The remedy is to dump out pooled water or bring these items indoors when not in use.
- Birdbaths are another danger area. The photo below shows birdbaths in a statuary store. Mosquitoes carrying St. Louis encephalitis were breeding here during an outbreak in 1964.
CDC, 1964
- Clogged and bent rain gutters are another haven for container-breeding mosquitoes. Gutters should be cleaned regularly, and bent areas in which water can pool should be repaired or replaced.
- Plastic-lined ornamental pools and ponds can be kept mosquito free by application of mosquito-specific poisons. Treatments called "mosquito dunks", available at garden centers and elsewhere, prevent mosquitoes from breeding here. If the pool can support fish, there are several species of ornamental fish that feed on mosquito larvae and pupae that can be purchased. If dragonflies are breeding in your pond, leave them alone. They are voracious predators of mosquitoes.
- Discarded items such as old tires, cans, bottles, etc., collect water easily and should be drained or moved to a proper disposal area.
- Gardening items including watering cans and saucers under flowerpots should also be drained frequently.
- All sorts of other items can hold enough water to breed mosquitoes: empty trash cans and upended lids, unused kiddie pools, plastic pool covers and much more. Again, the simplest method to eliminate mosquito larvae and pupae is to remove accumulated water from these items. Items that need to hold water, such as water bowls for pets, should have their water changed regularly.
- Other species of mosquitoes prefer the soil-bottomed breeding areas avoided by container-breeding species. Because of this, areas including puddles under air conditioners, pooled water on lawns, drainage ditches, etc., are common breeding grounds. Most of these areas can be dried, filled in with soil, or treated with an appropriate insecticide.
Keep mosquitoes out of your house
Make sure that door and window screens fit securely and do not have tears. Don't leave screenless doors and windows open for prolonged periods. If you have air conditioning, use it if you don't have window screens.
Protect yourself
- Wear long sleeves, long pants and socks outdoors if at all appropriate. Mosquitoes are attracted to bright colors, so the clothing should be light colored. Mosquitoes can bite through clothing, but mosquito repellents containing permethrin can be applied to clothing. Permethrin is a highly effective repellent and insecticide (arthropodicide?) against mosquitoes, ticks and other arthropods, but should not be applied directly to skin. It can be applied to clothing, shoes, tents and other camping gear, mosquito netting, etc.
- There are effective repellents that can be applied to skin. The CDC recommends using repellents registered with the United States Environmental Protection Agency (EPA) as being safe for human health and the environment when used as directed. These repellents include those containing DEET, IR3535, picaridin, and some repellents containing lemon eucalyptus oil. The EPA is in the process of developing new labels for insect repellents to help consumers understand how to use them. This is similar to SPF labels that have become standard on sunscreen. The current proposed label shows whether the repellent works against mosquitoes, ticks or both; it also shows how frequently the repellent should be reapplied. The images below are from the EPA and not subject to copyright.
For more information
For more information about mosquito control, including insect repellent safety concerns, see the following resources.