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

Organizing, Operating and Maintaining an Integrated Community-Wide or County-Wide Mosquito Control Program

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

Introduction

Adult mosquitoes can transmit many diseases to man and animals. In Georgia, we are fortunate that mosquitoes only transmit a few of the many possible diseases that they are capable of transmitting. Of public health concern is the newly arrived West Nile virus (WNV), LaCrosse encephalitis (LAC), St. Louis encephalitis (SLE), and Eastern equine encephalitis (EEE); and in animals diseases such as heartworm of dogs and WNV and EEE in horses. Prior to the arrival of WNV, the major importance of mosquitoes in Georgia in recent times was that they are serious nuisance pests and interfere with outdoor work and recreation activities. Today, the decision to initiate mosquito control programs is influenced by the threat of vector borne disease in man and animals and the economic impacts of nuisance populations.

Individual homeowners can do many things to alleviate mosquito problems around their homes (eliminate standing water, repair screens, trim vegetation, residual treatments). However, control measures over limited areas are usually not the only answer, because adult mosquitoes often fly a mile or more from breeding sites and will quickly reinfest small, treated areas. To be most effective, mosquito control programs should be organized and operated over large areas. This requires organized efforts at the community, and often at city and county levels.

Many communities in Georgia would benefit from an organized, integrated mosquito control program. Organized mosquito control programs are normally initiated after citizens have expressed concern about mosquitoes to elected officials, county extension personnel, county health personnel and city managers. When sufficient levels of concern have been reached, a meeting is normally held to discuss the feasibility of organizing a mosquito control program. Careful planning will determine the need, size, scope, etc. of the proposed program. To have the best chance for success, the program should involve the five components of an integrated mosquito management program: Public Education/Communication, Surveillance, Source Reduction, Larviciding and Adulticiding when needed.

Public education is needed to inform the public about basic mosquito biology and what they can do to reduce the local mosquito population. This aspect is often the most effective technique to reduce container breeding mosquitoes in neighborhoods and can be conducted through water/sewer bill mailings, public service messages and local radio and television stations. It is also important that all governmental agencies are informed and involved and are working together with the same goals and understanding.

Surveillance is needed to locate the sites where mosquito development is taking place. This activity can be the most time consuming aspect of an integrated program and needs to be conducted by trained, diligent employees. Once sites of mosquito breeding are located, it is important to map these sites for future reference. Often sites will be targeted year after year.

Source reduction is conducted to reduce standing water when possible, thereby reducing the sites that can support mosquito development. This activity is often labor and resource intensive, but can significantly reduce mosquito breeding in some areas. It is important that source reduction is conducted in an environmentally sensitive manner, as bottomland, aquatic environments are often some of the most ecologically diverse and important sites around our communities.

Larvicide applications are used when source reduction techniques cannot be conducted in an environmentally sound manner to eliminate a particular habitat. Larvicide applications can be time consuming and require trained employees, but can be very effective in targeting mosquito populations while they are confined in specific sites.

Adulticide applications are used when the previously mentioned techniques are not entirely effective, unreasonable adult numbers are present or a significant threat of disease transmission has been identified. Adulticide applications must be conducted by trained employees with properly calibrated equipment.

Adult Mosquito Control

A key component of any mosquito control program is to provide relief to area residents from adult mosquitoes. This point is critical when the primary objective of the program is to prevent disease transmission.

An ultra low volume (ULV) sprayer can be purchased to provide effective, safe and economical adult mosquito control. ULV sprayers disperse tiny, microscopic droplets of insecticide. These machines can be very effective against adult mosquitoes, and are commonly used in Georgia. To determine the number of ULV sprayers needed, a recent edition of a city or county road map is examined to determine the length of streets and roads over which the ULV sprayer will be transported. ULV sprayers weigh approximately 500 pounds and are transported on wheeled vehicles or trailers that can travel 10 to 20 miles per hour. Only those streets running perpendicular to the prevailing wind should be treated.

Example

Wind direction

  Streets
1              
2              
3              
4              
5              
6              
<--------------------------------------2 miles---------------------------------------->


In the above example, there are 6 streets running perpendicular to the wind for a total of 12 miles (6x2).

Therefore, approximately half of the streets and roads in a given area are treated during each treatment. Another factor that should be considered is the size of the areas to be treated. In towns and cities, virtually all areas would be treated to protect individuals living in these areas. In more sparsely populated areas, usually only the areas of heaviest population density are treated. Sparsely populated areas don’t have the grid of streets to allow access, and treating such areas may not be cost effective. Large urban areas may find it desirable to underwrite the cost of control in surrounding rural areas to provide a buffer zone around populated areas. This factor is especially true in the coastal plain, where some species of mosquitoes may travel substantial distances from their breeding sites.

Prior to initiating a spray program, it is essential to obtain up-to-date city or county road maps with the streets and roads over which the sprayer will be transported clearly delineated. It is also necessary to know the length of the streets and roads to calculate the amount of insecticide that will be required for each application. Applications for most products and equipment are based, for planning purposes, on an effective swath width of approximately 300 feet or a normal city block.

Since wind currents help to move the insecticide over the treatment area, streets to be treated are those running perpendicular to the wind. Thus, if the city has 60 miles of streets, 30 miles running generally east to west and 30 miles of streets running north to south, then about 30 miles of streets would be treated during each night’s operation. When street patterns are convoluted and not in a “waffle” pattern, it may be necessary to adulticide on each street to get complete coverage.

The following companies sell ULV machines in Georgia:

1.    ADAPCO- London Fog ULV models
2800 S. Financial Court
Sanford, FL 32773-8118
(407) 330-4800
1-800-531-4320
(on-site repair)
Contact: Chris Pederson

2.    VOPAC (Formerly Van Waters and Rogers)
Curtis Dynafog ULV models
1186 Braddock Ave
North Charleston, SC 29405
Office (843) 767-3200
Mobile (843) 224-0223
Pager 1-877-705-2631
(on-site repair)
Contact: Kim Todd

3.    Clarke Mosquito Control Products- Leco ULV models
3405 SW 40th Blvd.
Suite 205
Gainesville, FL 32608
(904) 355-0012
1-800-323-5727
(on-site repair)
Contact: Mike Leahy

Costs vary depending on the ULV unit and accessory parts added. These companies also sell insecticides for mosquito programs. Sales representatives will provide specific price quotations and other needed assistance regarding the purchase, installation, use and maintenance of their ULV sprayers. If on-site repair is important to you, confirm whether or not such services will be available. The companies listed are those currently active in Georgia. It is not intended to suggest that other possible vendors are not equally satisfactory.

A suitable vehicle should be provided to transport the ULV sprayer. It is best to mount the ULV sprayer on the back of a small truck. If a truck cannot be provided, the ULV sprayer can be mounted on a trailer. This manner is the least preferred way to mount the ULV sprayer because trailers are difficult to maneuver. This situation creates problems that can result in damage to the trailer and the ULV sprayer when unskilled workers attempt to operate the system.

Every year new devices are being perfected for use on ULV sprayers to improve efficiency and safety. Automatic and variable flow control systems speed control systems and chart marking systems are available. These  “add-ons” will raise the basic cost of the unit.

At a minimum, the driver should be able to turn the sprayer on and off within the cab, and no insecticide should be piped through the cab.

Variable flow devices will automatically control the flow depending on the vehicle’s speed. For example, twice as much is emitted when the vehicle is going 20 miles per hour as when it slows to 10. When the vehicle stops it automatically cuts off. This device prevents over-treating, ensures the correct rate with variable speed, saves insecticide, and decreases the chances of doing damage to property or the environment. Variable flow devices are expensive and may not be cost effective unless there is enough insecticide used to be cost effective (typically 3 or more 55 gallon drums).

Chart making systems are a supervisory tool more commonly used in large mosquito control districts. They are mounted in the cab and will record the vehicle’s speed and sprayer operation over time. These sealed recorders give assurance to a supervisor that the equipment was operating at the required time and at the required speed.

Thermal foggers (oil based insecticide is dropped onto very hot metal such as oil “burning” from the exhaust of a car) are also available but are not recommended for applying up and down city streets. The insecticide for a thermal fogger will cost about twice as much as for a ULV unit, can be a fire hazard, and they can be a traffic hazard due to the fog emitted. An advantage of this system is that the operator and the public can see exactly where the insecticide is going in the environment.

Residents should remember that there is essentially no chemical residue with ULV or fogging applications. Once the tiny droplets dissipate, mosquitoes can begin to reenter the area treated from outside the treated area, or emerge as adults from breeding areas either within or outside of the treated area. This phenomenon is why mosquitoes will move back into small, treated areas very quickly, but take longer to repopulate larger treatment zones.

Permethrin, malathion or carbaryl can be used as a residual barrier treatment using non-thermal ULV equipment to treat plant foliage surfaces where mosquitoes may rest. While these are safe materials when used properly, there are environmental restrictions.

Recommended Insecticide

After the ULV sprayer has been purchased and properly mounted, insecticides must be ordered for use in the ULV sprayer. ULV sprayers utilize highly concentrated insecticides that may or may not need further dilution. Be sure the chemical you purchase is labeled for use in a ULV sprayer for mosquito control. There are three basic chemical classifications of insecticides currently available for mosquito adulticiding. These include organophosphates, natural pyrethrins and synthetic pyrethroids, and each classification has its own benefits and drawbacks.

The organophosphates have been used in mosquito control since the early 1950’s and are generally less expensive. Organophosphate toxicity is due to the inhibition of cholinesterase. This inhibition interferes with the neuromuscular junction and ultimately causes paralysis of the insect. Products in this class include malathion, naled and chlorpyrifos. Malathion (brand names Atrapa®, Fyfanon®) is the product of choice for many mosquito control programs throughout the country. Malathion-based products are typically more cost effective. The primary drawbacks of this material are a characteristic odor and its potential to damage painted surfaces at high rates (such as running the machine when not moving and wetting a vehicle down). Naled (Dibrom® & Trumphet®) is a highly effective material, but is highly corrosive to application equipment. This material is often the product of choice along the coast where salt-marsh mosquitoes are the primary target. Chlorpyrifos is available under the brand name MosquitoMist® and is a relatively inexpensive option. However, this product is most effective at the higher label rates.

Natural pyrethrins are extracted from Chrysanthemum flower heads grown commercially in parts of Africa and Asia. Natural pyrethrins (Pyrenone®) are not photostable and as a result breakdown quickly. Products in this group provide rapid knockdown of adult mosquitoes, but are relatively expensive to use.

Synthetic pyrethroids are mimics of natural pyrethrins and are the basis of many of the most commonly used adulticides. These products are not cholinesterase inhibitors, are non-corrosive and will not damage painted surfaces. In addition, they are less irritating than other mosquito adulticides and have a less offensive odor. In comparison to other adulticides, pyrethroids may be applied at much lower rates of active ingredient per acre. The disadvantage of these products is that they may be less effective in controlling salt-marsh mosquitoes than the organophosphates and they are generally more costly.

While malathion, permethrin and resmethrin are a few of the more popular and effective choices for adulticiding, there are several other materials that are equally effective. There are many factors that must be considered when determining the material of choice for a specific situation. The type of mosquitoes being targeted, the equipment available for the application, and the general resources of the operating agency will all come into play.

Application Instructions

During the months when mosquito populations are high, applications may be needed two or three times per week. During the hot, dry portions of the year only one, or perhaps no applications per week may be needed. No applications are typically needed during the winter months. Especially warms spells in the southern most portions of the state may require treatments during the winter period. Careful evaluation of the adult mosquito population will influence these decisions.

Before making an application, one must read, understand and follow all label instructions. It is illegal by State and Federal law to use an insecticide in any manner other than instructed by the label. Be sure spray particle sizes are correct and the driver is trained.

Before treating for adult mosquitoes, as a minimum, consider these factors:

    1. Adult Mosquito Activity
    2. Wind
    3. Temperature
    4. Time of Day

Adult Mosquito Activity

Adult mosquitoes should be present in the area to be treated and they should be active when the area is treated. This information can be obtained from one or all of the following:

    1. Mosquito Biting Counts
    2. Complaints from Residents
    3. Light Trap Collections
    4. Other Population Monitoring Devices

Most mosquito species that bite man are primarily active in the dawn and dusk periods. However, Aedes albopictus, the Asian tiger mosquito, has become one of our most common mosquitoes and is quite active in the morning and afternoon. This species is considered an aggressive daytime biter. Few of these container breeders will likely be killed by applications conducted after sunset or before sunrise.

If citizens are complaining primarily about day biting mosquitoes, organizing a ULV, evening spray program, may provide little relief. Public education and community wide involvement in removing or emptying breeding sites and containers is needed[1]. As with any type of pest control, properly identifying the pest species and its habitats is critical to the success of the program.

Wind Movement

To be most effective, the insecticide should be dispersed over the area to be treated by wind currents of 1-10 miles per hour, preferably 4-6 mph. Do not treat when the wind speed is too high, during a heavy rain (treating during a light rain is allowed if adult mosquitoes are active), when no wind is blowing or when the insecticide is not remaining near the ground.

Temperature

Mosquitoes are more active and the insecticide is more effective when temperatures range above 60°F during treatment.


Time of Day

Temperature conditions, temperature inversion layers, wind movement and mosquito activity are normally best for treatment from 7:00 p.m. to about 10:00 p.m. in the evening or in the early morning hours up to about 9:00 a.m. ULV treatments should be made during this period for maximum efficacy. Realistically, applications are usually conducted based on a compromise of a variety of factors including operational constraints, human interactions, weather/seasonal conditions and mosquito activity. It should be noted, that treatments targeting the Asian tiger mosquito will have some effect if conducted prior to sunset in the evening or immediately after sunrise in the morning. When mosquitoes are not active, they are usually resting in protected areas where it will be much more difficult for the insecticide droplets to be efficacious.

Controlling Mosquito Larvae

When local citizens are protected from adult mosquitoes, then attention should be directed to mosquito breeding areas where temporary and long-term mosquito control measures can be initiated. The following measures should be considered for implementation: provide homeowners with information about mosquito breeding areas and ways the areas can be altered to control mosquito breeding, conduct city/community wide cleanup programs to remove/eliminate breeding containers and sites (such as containers, used tires, litter in general), drain/alter/eliminate mosquito breeding areas, and initiating larviciding of remaining breeding sites. Common larvicides include the biological control agents Bacillus thuringiensis var. israeliensis or Bti (trade names Aquabac®, Bti Briquets®, Teknar® and Vectobac®) and Bacillus sphaericus (trade name Vectolex®), the monomolecular surface film (trade name Agnique®), the insect growth regulator, methoprene (trade name Altosid®) and the organophosphate, temephos (trade name Abate®). The species being targeted, habitat, equipment available, labor availability and agency resources will dictate which of these materials is the best choice for each situation. All of these products are effective and safe when used as directed by the label.

Public Relations

Since community adulticiding involves applying pesticide across the property of private residences, it is essential to explain the reasoning behind the program through the local media before initiating treatments. The safety of the pesticides to be used and how they will be applied should be described. For any resident who objects to the ULV application across their property or claim a sensitivity to the chemical, one or both of the following is suggested:

  1. Call the homeowner and inform them when the spray truck will be coming by their homes so they can close windows, stay inside, etc.
  2. Have the spray truck operator turn off the sprayer when near such a homeowner’s property.

Public support is essential for a successful program. Ignoring the concerns expressed by citizens will be damaging to the overall support of the program.

Remember – Day biting mosquitoes have taken shelter in the late evening when most ULV applications are conducted. As a result, you will not usually get good control of these day biters (primarily the Asian tiger mosquito). ULV applications during the day can be effectiveness against this pest, however there is only a short period in the evening and morning when conditions are usually acceptably to conduct applications and consequently only limited areas can be covered each day. It is also impractical for most mosquito control programs to apply insecticides to individual containers – such as tires (where the Asian tiger mosquito breeds), on private premises. The public needs to know that the best way to control this pest is by disposing or emptying artificial containers and small pools of water on their property and encouraging their neighbors to do the same. This species is not a strong flier, often not traveling more than 300 feet from its larval habitat. Consequently, when this species is present, it indicates that it is usually developing in the near vicinity. Expectations from the public that a governmental mosquito control program will eliminate day biting mosquitoes on their property is unrealistic and will surely lead to disappointment, thus the educational component of the program is essential.

Additional Assistance

For more information contact your local County Extension Agent.

ATTENTION!
Pesticide Precautions

  1. Observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
  2. Store all pesticides in original containers with labels intact and behind locked doors. “KEEP PESTICIDES OUT OF THE REACH OF CHILDREN”.
  3. Use pesticides at correct label dosages and intervals to avoid illegal residues or injury to plants and animals.
  4. Apply pesticides carefully to avoid drift or contamination of non-target areas.
  5. Surplus pesticides and containers should be disposed of in accordance with label instructions so that contamination of water and other hazards will not result.
  6. Follow directions on the pesticide label regarding restrictions as required by State and Federal Laws and Regulations.
  7. Avoid any action that may threaten an Endangered Species or its habit. Your county extension agent can inform you of Endangered Species in your area, help you identify them, and through the Fish and Wildlife Field Office identify actions that may threaten Endangered Species or their habitat.

Trade and brand names are used only for information. The University of Georgia Cooperative Extension Service and the College of Agricultural and Environmental Sciences does not guarantee nor warrant published standards on any product mentioned; neither does the use of the trade or brand name imply approval of any product to the exclusion of others which may also be suitable.

Revised and updated by Elmer Gray and Ray Noblet, University of Georgia,
Cooperative Extension Service and the Department of Entomology.
September 18, 2002

Controlling Mosquitoes Around Our Homes and Neighborhoods.  Cooperative Extension Service.  4pp. September 17, 2002.  E. W. Gray & R. Noblet

The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service, University of Georgia College of Agricultural and Environmental Sciences offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability. An equal opportunity/affirmative action organization committed to a diverse work force.


September 2002

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.

 Gale A. Buchanan, Dean and Director

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