West Nile Virus and Eastern Equine Encephalitis -- Information for Homeowners
There are a number of things that homeowners can do to reduce the likelihood of mosquitoes breeding or congregating near their homes. Some activities cause no risk or a relatively low risk to the environment and do not require a prior license from a state agency. Others require a license. The following list begins with the lower-risk activities, and ends with the higher-risk activities.
Remove containers that catch or collect water. Mosquitoes can breed in man-made sources of stagnant water around the home. These breeding areas include ceramic pots, clogged gutters, buckets, old tires, pool covers, and old pet dishes. Change water in bird baths frequently, and tip up the wheelbarrow so it doesn't collect water. Go here for more ideas on avoiding stagnant water around your home, potential vectors for WNV, and mosquitoes in general.
Reduce adult resting sites. Promote natural breezes to discourage mosquitoes by cutting back dense brush and keeping areas mowed right around the house. However, while dealing with the mosquitoes, keep in mind that damaging natural vegetative buffers near a protected natural resources, such as a lake or stream, has impacts on the health of the waterbody, and may require a permit from the DEP (see Licensing Page).
Encourage and protect native species that eat mosquitoes. Many native species eat mosquitoes, including dragonflies, bats, birds, frogs, and fish. Be careful not to import and release non-native species, as they can cause problems in native habitats. Information on illegal fish stockings (off-site).
Add window screens where absent, and fix damaged screens. Basic maintenance.
Keep outdoor lighting to a minimum. Outdoor lighting attracts mosquitoes, as well as consuming energy and running up the electric bill.
Personal protection -- use protective clothing and insect protection wisely. A number of repellants are available. Protective clothing can include mosquito netting designed to be worn, as well as ordinary long sleeved shirts, long pants, and gloves. Insect netting over a bed at a camp can also provide good protection at night. Avoid wearing scents that attract insects! Link to information on repellents (off-site).
Chemical and bacterial pesticides. The use of pesticides, particularly the use of pesticides in water, is highly regulated because of the significant risks that pesticides pose to water quality, the natural environment, and human health. Most approaches and methods require a permit from the DEP.
Various chemical and bacterial agents are marketed for control of mosquitoes. Chemical pesticides are not selective and have the potential to impact other species. Bacterial pesticides are developed to impact species with specific properties, but may also impact more species than desired. For example, the bacterial pesticides Bti (Bacillus thuringiensis var. israelensis) and Bs (B. sphaericus) work on alkaline pH guts, which are found in mosquitoes, black flies, and some non-biting midges. Other bacterial agents may also affect butterflies and moths. Application of either type of pesticide to waters of the State requires a DEP permit. When a pesticide application to dry land could potentially reach waters of the State during the time the pesticide is active, a DEP permit is required pursuant to Chapter 514.
However, the following control methods are available to homeowners without requiring a permit. They still have risks, so they should only be used when really necessary. Remember that most kinds of mosquitoes do not carry WNV or EEE, but do provide a source of food to other desirable organisms.
Spraying for adult mosquitoes -- Pesticides used away from waterbodies and wetlands. Treatments for killing adult mosquitoes, done with appropriate precautions to avoid water, including ground or aerial applications done according to the pesticide label instructions, do not require a permit from the DEP. However, they may require a license from the Board of Pesticides Control.
A property owner may apply over-the-counter mosquito controls on his or her own property to trees, shrubs and other upland vegetation. Another option is to treat water in containers, i.e., dumpsters, old tires, birdbaths or other breeding sites not connected to any waters of the State. Neither of these activities requires a commercial pesticide applicator license.
Direct applications to water for mosquitoe larvae (larvicides) -- Non-chemical pesticides. The DEP has determined that some means of non-chemical pesticide treatments can be conducted under specific conditions without Department approval. Mosquitoes, black flies, and some non-biting midges have physiological differences from other species that make them particularly sensitive to the bacterial pesticides Bacillus thuringiensis, var. israelensis (Bti) and B. sphaericus (Bs).
These materials are available in solid and granular formulations that sink to the bottom, will not be released into the water column, and must be ingested to be effective. They also have limited persistence in the environment. Based on this, treatments of solid or granular formulations of Bti or Bs as larvicides may be used in the following situations, as long as label instructions are followed.
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Artificial containers that can not be emptied, such as catch basins. A "catch basin" is typically a concrete chamber with a metal grate opening at the top set flush with pavement. Stormwater runoff directed to the grate collects in the chamber below and is then discharged through a series of pipes to a receiving area. This collection of pipes and basins is referred to as a stormwater sewer or storm sewer.
- High elevation salt marsh pools that contain mosquito larvae but no natural predators. "High elevation salt marsh pools" are natural pools that are located above the normal high tide line. These areas are typically only flooded during significant storms or other extremely high tide events, often only once per month. Some of them contain fish that will act as natural predators. The pools without fish provide mosquito breeding habitat.
- Isolated, freshwater wetlands. "Isolated freshwater wetlands" are wetlands contained on one person's property that have no connection to other surface waterbodies. Freshwater wetlands can contain natural predators of mosquitoes too, such as fish.
- Private, constructed ponds. Private, constructed ponds that are contained on one person's property and have no connection to other surface waterbodies.
DEP emphasizes that people need to inspect “habitats” to make sure that stagnant, breeding conditions exist, that mosquito larvae are present, and that there are no natural predators that will take care of the mosquitoes on their own before using a larvicide.
Any other discharge of chemical pesticides to a water of the State, or treatment using a bacterial pesticide in any other habitat areas, requires approval from the DEP.
Always remember, "Think First, Spray Last"
