The Wetland Habitat and Mosquito Management (WHAMM) Program of the DEP's Wildlife Division uses an integrated pest management (IPM) approach to mosquito management that includes public education, mosquito level monitoring and chemical, biological and cultural control methods. Control measures are initiated when immature (larval) mosquito levels reach certain threshold limits. Additional steps are taken to reduce adult mosquito populations when viruses like EEE or WNV are detected in mosquitoes. Chemical insecticides are strategically applied by ground or aerial application equipment to control larvae and/or adults. The insecticides used are registered by the U.S. Environmental Protection Agency and the Connecticut DEP and do not pose any health hazards to humans or the environment when used as directed. Long-term control using water management is the preferred method for managing mosquitoes, particularly in tidal wetlands. Public education which promotes eliminating mosquito-breeding sites around the home is also a crucial component of Connecticut's Mosquito Management Program.

 

Managing Mosquitoes Using Insecticides
Insecticides used for mosquito management are grouped into two categories. Larvicides are used to control immature (larval) mosquitoes in aquatic habitats. Adulticides are used to control adult mosquitoes. All insecticides used by the WHAMM  Program are registered with the U.S. Environmental Protection Agency and the DEP's Pesticide Unit. They do not pose any adverse threat to humans or the environment when used in accordance with the label.

 

Larviciding is the most efficient and effective chemical method of managing mosquitoes because the larvae are concentrated in relatively small, well-defined, aquatic habitats. Larvicides are applied, by hand or aerial application equipment, to mosquito-breeding habitats when there is an abundance of larvae. If larval control methods are successful, the need for adult mosquito management is greatly reduced or eliminated. Currently, the primary larvicide used by the WHAMM Program is the bacterial compound Bti (Bacillus thuringiensis var. israelensis). Bti must be ingested by the feeding larvae to be effective. Bti targets mosquitoes but can affect other flies such as black flies and some midges. It has a short effective life (two to three days) and must be reapplied to each new generation of mosquitoes.

 

Chemical control using adulticides to reduce the adult mosquito population is considered when a public health threat from EEE or WNV exists.  Adulticiding provides an immediate but short-term reduction in adult mosquito numbers. Truck-mounted equipment is used to create tiny, ultra-low volume (ULV) droplets of insecticide that drift through the swarm of mosquitoes. Truck-mounted applications are used in relatively small, localized areas where road access allows adequate coverage. If, however, the public health threat exists in a larger geographic area, where truck-mounted spraying would be ineffective, aircraft can be used to aerially-apply adulticides.  The primary adulticide used by the WHAMM Program is resmethrin, a synthetic pyrethroid. This product has the same active ingredient as several over-the-counter yard and veterinary sprays. Resmethrin is short-lived (breaks down within one to four hours) and must be reapplied to each mosquito infestation. It does not pose any adverse threat to humans and the environment when applied as directed. Adulticiding is more costly than larviciding because adulticides are usually applied over larger areas.

 

The WHAMM Program is actively evaluating new mosquito control products as they become available. New products must provide consistent mosquito control, be environmentally safe and nonhazardous to humans and be cost-effective. If new products meet these requirements, they are considered for possible use.

 

{Equipment excavating ponds and channels}

Low ground pressure equipment is used to excavate shallow ponds and channels on the marsh surface. These ponds provide habitat for mosquito-eating killifish and other wildlife.

Mosquito Control Using Water Management
Where possible, the WHAMM Program uses water management to alter sites, making them unsuitable for mosquito egg and larval development and enhancing the area to provide habitat for natural mosquito predators such as fish and birds. This method provides more permanent mosquito management than chemical insecticides, resulting in a substantial reduction in insecticide applications and costs.

 

In tidal saltmarshes, a technique known as Open Marsh Water Management (OMWM) is the preferred control method. Unlike the parallel grid-ditch method used in the 1930s to drain wetlands, OMWM involves the selective excavation of shallow ponds and ditches in mosquito-breeding areas. These pond and ditch networks are not connected directly to tidal channels and, therefore, do not drain at low tide. After excavation, a higher water level is maintained, which provides habitat for fish and other wildlife and encourages revegetation by native marsh grasses. {Killifish} Mosquito management is achieved by modifying egg-laying sites and by creating open water habitat for small naturally-abundant killifish, which prey on mosquito larvae and pupae. OMWM systems provide long-term control of mosquitoes, thus reducing the need to apply chemical insecticides.

 

Mosquito Management Around the Home
There are several ways homeowners can minimize the number of biting mosquitoes in their yards. One of the easiest and surest ways to manage mosquitoes around the home is to eliminate standing water where mosquitoes can lay eggs. Some common mosquito breeding sites around the home are:

Homeowners should dispose of or recycle trash which can hold rainwater and flush bird baths and wading pools weekly. Swimming pool filtering systems should be maintained in good working order. Openings for standing water sources, such as septic tanks or rain barrels, can be sealed or covered with screen. Rotten stumps and tree holes should be filled with sand. Old tires should be disposed of properly or holes (0.5 inches or larger) can be drilled in the bottom of the tires to drain rainwater. The tires can also be stacked and covered with a tarp to prevent rainwater from entering. Lawns and gardens should be watered minimally to prevent puddling.

 

Ornamental pools and aquatic gardens can breed mosquitoes if the water is allowed to stagnate. Water should be changed frequently or an aerator can be installed. Homeowners can practice their own biological control by stocking minnows, such as Gambusia or guppies, which will eat mosquito larvae. The fish will need to be restocked annually because they will not survive the winter. Large pond stocking or releasing fish into public waters is prohibited. Insecticides, such as Bti, are available at many nurseries and garden supply centers and can be used to treat mosquito breeding sites. In general, most natural ponds and lakes are not usually sources of mosquito breeding. Furthermore, permanent bodies of water usually contain fish and other predators that would eat mosquito larvae, if present.

 

There are also ways homeowners can minimize the annoyance caused by adult mosquitoes. Mosquitoes prefer to rest in shady, calm areas and will avoid more open sunny, breezy areas. Removing tall weeds and mowing tall grass will reduce places where mosquitoes can rest. Mosquitoes are most active around dawn and dusk (some, such as the common saltmarsh mosquito, may be active throughout the day). Simply avoiding activity during these peak mosquito times can minimize contact with mosquitoes.

 

To reduce the chance of being bitten when outside, wear protective clothing such as long sleeves, long pants and head cover. Light-colored, loose-fitting clothing is preferable because dark clothing radiates more heat and attracts more mosquitoes. Insect repellents containing DEET can be used by most people and are often effective.  Permethrin, a synthetic pyrethroid that is widely available for repelling ticks, also repels mosquitoes. It is applied to clothing and provides longer-lasting protection. Although not marketed as repellents, there are several cosmetic liquids and creams that claim some level of mosquito repellency. These products may effectively repel when mosquito pressure is light, but need to be reapplied frequently.

 

Homeowners may also consider spraying insecticides to shade trees, hedges and shrubs adjacent to the foundation of structures. There are several over-the-counter sprays that homeowners can use to control mosquitoes. Always read and follow the label. Private, certified applicators can also be hired to treat yards and neighborhoods. Make sure the applicator is certified in the "Mosquito and Biting Fly" category by the DEP Pesticide Unit.

 

To reduce mosquito infestations in the house, maintain screens over doors and windows. A porch or deck also can be enclosed with screening. Outside light use should be reduced and yellow lightbulbs used when possible.

 

As mentioned earlier, EEE is frequently fatal to horses. Horse owners are strongly encouraged to protect their horses from EEE by inoculation. There is currently no vaccine for WNV. Canine heartworm (filariasis) is a fatal disease circulated within the dog population by biting mosquitoes. The DEP, CAES or DPH do not monitor for heartworm in mosquitoes. Dog owners are encouraged to protect their pets from canine heartworm by administering preventative medications obtained through their veterinarian.

 

Mosquito Myths
A number of products on the market claim to have mosquito control capabilities. In most cases, these products have not been rigorously tested and do not perform as advertised. Mechanical traps, such as ultraviolet “bug zappers” or devices that repel using ultrasonic sound waves, do not meet advertisers claims. In fact, bug zappers attract few mosquitoes and may actually kill beneficial insect predators. Therefore, they should not be used for mosquito reduction. Natural products, such as citronella plants, clove oil, peppermint or diet supplements like garlic or vitamins, claim to repel mosquitoes but there is no scientific evidence to support such claims. There are many individuals who feel these products are effective; however, they may not be effective for everyone. Natural predators, such as bats and some birds, eat adult mosquitoes.  However, some studies have shown that mosquitoes make up less than 10 percent of a bat's or bird's diet. Bats and birds can reduce the severity of an infestation but will not eliminate all of the mosquitoes in an area.