Mosquito Control Program

Phone 301-258-6310 Fax 301-948-6149 Email environment@gaithersburgmd.gov

The City of Gaithersburg Mosquito Control Program ’s major goal is to solicit public involvement to implement a proactive mosquito-borne disease prevention program. The program emphasizes the public health aspects of disease prevention, and concentrates on mosquito surveillance, larviciding, and public education for the control of mosquitoes and arboviral diseases such as the West Nile Virus (WNV).

Program Objectives

Gaithersburg ’s Mosquito Control Program's major objectives are to:

• Solicit public participation in reducing the health risk associated with infectious mosquito vectors through public education initiatives;
• Provide homeowners with site visits, information and encouragement to eliminate potential breeding sites in pools and containers around the home;
• Identify and record potential and historical mosquito breeding sites located on City-owned and HOA property; and
• Monitor identified breeding sites on City-owned or HOA property and apply environmentally friendly larvicide where mosquito larvae are present.

Mosquitoes in Gaithersburg

In the fall of 2005, an entomologist from Maryland Department of Agriculture’s Mosquito Control Division inspected homes, yards, inlets and lakes and provided the City with recommendations on how to reduce and eliminate mosquito breeding sites in the community. Typical species found during the inspections were Culex and Anopheles species which are usually active in the dawn and dusk hours, and are typically less active during the day. 

Notably, MDA reported that the reason for the increase in mosquito complaints is because the Asian tiger mosquito (Aedes albopictus) has migrated to this area. The Asian tiger mosquito is an exotic species introduced to North America from Asia and has become a major pest throughout the entire Washington Metropolitan region. The name "tiger mosquito" comes from its white and black color pattern - it has a white stripe running down the center of its head and back with white bands on the legs.

The tiger mosquito prefers older residential areas where shade and water-holding containers are common. The natural breeding site for an Asian Tiger is a tree hole. This species has, however, adapted to breeding in any type of container including plant whorls, flower pots, plastic drainage pipes, gutters, bird baths, and even bottle caps ... if it can hold water it can breed Asian Tigers - the one small consolation is that the tiger mosquito will not breed in ditches, marshes, lakes, or swale water.

While most species feed at dawn and dusk and rest in the foliage during the day, the Asian Tiger is an aggressive day-biter and will readily leave its shady resting area to feed, even in the direct sun. However, the tiger mosquito usually does not fly far (100 yards) from its breeding site, so if you have Asian Tigers look carefully around your property or your adjacent neighbors' property for their source.

Because of its breeding habitat and daytime activity period, the Asian Tiger has become a significant domestic mosquito problem. The application of larvicides to control tiger mosquitoes is generally ineffective due to the large number and cryptic location of breeding sites and is therefore so labor intensive that it is beyond the resources of public agency mosquito control programs.Spraying for tiger mosquitoes is also generally ineffective because they are active during the day when there are inappropriate atmospheric conditions for spraying and a higher potential risk to human exposure.

The most effective method of controlling tiger mosquitoes is reducing or eliminating the containers which are the source of the problem. Draining or removal of water holding containers, even on a localized basis, will produce remarkable long-term reductions in mosquito annoyance. For this reason, it is necessary to engage the public to frequently check their properties and eliminate standing water. These breeding sites are the easiest to eliminate provided there is the cooperation of the homeowner.

What Are Common Mosquito Breeding Habitats?

All mosquitoes require standing water to breed, and most mosquitoes do not fly far from the location where they were bred to feed.  Thus one of the best ways to reduce the number of mosquitoes in your yard is to implement a regular (weekly) program to dispose of accumulated water.

The mosquito development process requires that water be standing or stagnant FOR ABOUT A WEEK.  This is important to note because some people have become unnecessarily concerned about water that naturally evaporates or drains away within a few days. For instance, after a heavy rainstorm there may be standing water in ditches and swales at the side of roads, in tire ruts on construction sites, or in puddles on the road. If the water is gone in a week or less, mosquitoes will not breed in these locations because they will not be able to complete their life cycle. Mosquitoes also do not breed in moving water, such as in streams or in ponds that have water flushing through them frequently.

The majority of mosquito problems around the house can be traced to small containers that hold water for at least one week.  Old bottles, cups, flowerpots and saucers, birdbaths, tree holes and drainage pipes are very good locations for mosquitoes to breed.  Leaf-filled gutters are also particularly good places for mosquitoes to breed.

Ways You Can Reduce the Number of Mosquito Breeding Habitats In and Around Your Home?

1. Interrupt the hatching process by dumping water every few days from birdbaths, pools, fishponds and unused flowerpots and vases. Pour water from saucers and plates underneath planters.
2. Clean leaf-filled gutters to allow proper drainage.
3. Turn buckets, baby pools, boats and other outside containers upside down when they are not in use.
4. Check for water pockets on grills, furniture, roofs, and tarps used to cover pools.
5. Keep shrubs and bushes trimmed and free of undergrowth to deprive mosquitoes of a favorite resting place, the underside of leaves.
6. Shake out the first few feet of garden hoses, and drain tubular lawn furniture, garden ornaments and kids' toys.
7. Throw away old bottles, cans and plastic containers.
8. Screen or cover rain barrels, garbage cans and other large containers.  Screen open ends of corrugated plastic drainage pipes.
9. Properly dispose of old and used tires.
10. Fill in tree holes with sand or plaster of paris.
11. Repair leaky water faucets, water hoses and air conditioners.
12. Prevent breeding in ornamental ponds by routine cleaning, stocking them with fish, installing an aerator to keep the water moving, or using mosquito dunks that can be bought at home improvement or hardware stores.

Remember: Mosquitoes need water to stand for five to ten days to breed, so first try to reduce the number of areas where water may collect and then to reduce the length of time water will sit.

How Does Gaithersburg Control Mosquitoes?

Program Overview

1. Mosquito monitoring and larvicide treatment program: For several years, the City has participated in Maryland Department of Agriculture’s cooperative mosquito control program. MDA monitors City and homeowner’s association (HOA) properties that have a history of breeding, and treats areas with a larvicide. A map depicting current mosquito monitoring and treatment locations is available.
   
   Monitoring of mosquito larva consists of walking the site to physically dip a cup of standing water to observe the developing larva. When an infested pool is identified a larvicide chemical is applied directly to the water that kills the mosquito larva before it reaches the next stage of development.
   
   Insecticide application directed against larval mosquitoes is an important component of an IPM mosquito control program. Larviciding is the most efficient type of temporary control. It is easier and more economical to eradicate or substantially diminish a brood of mosquitoes while they are concentrated as larvae in the aquatic habitat than to control them as adults. MDA’s Mosquito Control website (www.mda.state.md.us/plants-pests/mosquito_control/mosquito_control_program_description.php) provides more detailed information on the insecticides currently used in their larvicide program. Monitoring and larvicide control is a preferable mosquito management option because it is more accurate, longer lasting, cost effective, and only affects mosquito larva (not other organisms).
   
   In addition, since MDA starts their program in May and conducts monthly site visits, the City supplements this program by sending trained staff to start the treatment program in April and conduct biweekly monitoring of the ephemeral streams throughout the season.
   
   Most experts agree that targeting mosquito larva is the most effective and environmentally sound method. Here you are getting the mosquito before it reaches the stage where it can bite, and just as importantly, the treatment does not affect any other organisms, only the mosquito larva.
   
   
2. Public education: Breeding sites are easy to eliminate, provided that there is the cooperation of the homeowner. For this reason, the Gaithersburg provides free information on the City’s website, Cable TV, and brochures to help homeowners eliminate breeding site on private property.
   
   
3. Staff training: City staff is trained to inspect sites for breeding and to recommend ways to reduce and eliminate breeding habitat.

   Please Note: MDA does not conduct adult spraying in Montgomery County and since the Asian tiger mosquito is active during the day, this method is generally ineffective at controlling Tiger mosquitoes because of inappropriate atmospheric conditions during daylight hours and a higher potential risk to human exposure.

   Since fogging can be toxic to fish/aquatic organisms and beneficial insects, it requires public notification, a certified contractor and it is not part of MDA’s standard treatment program in Montgomery County ; therefore, the City does not implement a fogging program.
   

Where Does the Gaithersburg Use Larvicide to Control Mosquitoes?

The City does not treat private property; however, the City does treat City and HOA-owned property. A map is available depicting current mosquito monitoring and treatment locations is available.

Mosquito Monitoring and Treatment Locations:

Bennington Blohm Park Bridalwood Christman Pond Gateway Commons Girard Place Hidden Creek Land Bay 3 Inspiration Lake Kentlands Weirs Lake Helene Lake Lynette Lake Nirvana Lake Placid Lake Sheila Lake Varuna

Lakelands Ridge Malcolm King Park Park Summit Quarry Quince Orchard Park Ponds 1 and 2 Saybrooke Summit Hall Farm at Bohrer Park Back Pond Summit Hall Farm at Bohrer Park Front Pond Three Sisters Lake Turtle Pond Victory Farm Park Washingtonian Woods Watkins Mill Pond Woodland Hills Woods at Muddy Branch

Mosquito monitoring and treatment location map (pdf file)

Want the City to Examine Your Yard?

The City has trained staff that will visit and meet with you if you request a site visit.  On-site, staff will evaluate and make recommendations to help reduce, prevent or solve mosquito problems. 

Need More Information?

If you have a mosquito problem at home, or just want to ask a few questions. 
Contact the City of Gaithersburg :
Telephone: 301-258-6330
Email: environment@gaithersburgmd.gov

For other mosquito information contact the Maryland Department of Agriculture’s Mosquito Control Division at 410-841-5870.

Mosquito-Related Links

• Maryland Department of Agriculture Mosquito Control : Fact sheets, health issues and other general information on pest management for the State of Maryland.
  www.mda.state.md.us/plants-pests/mosquito_control/index.php

• Montgomery County Department of Environmental Protection: West Nile virus information.
  www6.montgomerycountymd.gov/content/pio/pdfs/west_nile_virus.pdf (pdf file)

• US EPA Mosquito Control: Biology and control information.
  www.epa.gov/pesticides/health/mosquitoes

• Centers for Disease Control and Prevention Fact Sheet: West Nile Virus
  www.cdc.gov/ncidod/dvbid/westnile/wnv_factSheet.htm

• Maryland Department of Health and Mental Hygiene West Nile Virus Information
  ideha.dhmh.md.gov/OIDEOR/CZVBD/SitePages/west-nile.aspx

Links to the outside information sources listed above are provided as a courtesy only. The City of Gaithersburg is not responsible for the information they contain. These links do not represent or imply the endorsement of the policies and/or products of the outside agencies or organizations in question.