FAQs

Why Use an Integrated Pest Management (IPM) Program for Mosquito Control?

“Successful IPM utilizes a combination of control strategies, including surveillance, source reduction, larvaciding, adulticiding (only when necessary), biological control and education. Adulticiding alone is ineffective in controlling mosquito populations because it is difficult to get the adulticide to the inaccessible habitat of the adults. Mosquito larvae are left to continue their development and they quickly replace the adults. In fact, mosquitoes can build up a resistance if they are overused. Aside from the ineffectiveness, pesticides can have long term ecological, environmental and health impacts. The EPA encourages nonchemical mosquito control measures; therefore, in an IPM approach to mosquito control, adulticides play only a small part in overall mosquito control.” – West Virginia Department of Health and Human Resources, Bureau for Public Health, June 2002

What is Mosquito Surveillance?

Surveillance identifies locations where mosquito populations are building, so targeted control measures can be implemented before a problem exists. Surveillance is the foundation on which any mosquito control program should be based. Larval surveillance is done by sampling a wide variety of habitats. Surveillance of adults targets mosquitoes which are no longer in the larval habitat. Traps for adult mosquitoes include CDC light traps which may be baited with carbon dioxide. These traps are used to capture mosquitoes looking for a blood meal. Gravid traps are frequently used to sample Culex mosquitoes ready to lay eggs. Surveillance is also used to determine the mosquito species in a given area, allowing us to recognize the species that can carry disease. Nuisance mosquito calls from the public can serve as places to start mosquito surveillance.

What is Larviciding?

Larviciding is the adding of chemical or other products to a water source to kill mosquito larvae and pupae. Controlling the larvae is more effective than adulticiding. Chemicals available include Insect Growth Regulators (IGRs), which prevent the larvae from completing their development. Chemical control of larvae should only be carried out by trained personnel or at their instruction. Several “biological” larvicides (bacteria registered as pesticides), which are safe and easy to use, are available as control agents. These include Bacillus thuringiensis var. israelensis (Bti) and B. sphaericus which are available commercially.

What is Adulticiding?

Adulticiding is a process aimed at reducing the number of adult disease-carrying and pest mosquitoes by evening spraying of residential areas with ultra low-volume (ULV) mist
spray equipment. The Health District uses a permethrin-based insecticide, which is a man-made version of Pyrethrin which is derived from plants in the Chrysanthemum family. This adulticide is mixed with ten parts of food grade oil. Driving at 10 miles per hour, 1.031 ounces of Permethrin is sprayed per mile. Adulticiding is the last line of defense in the control of mosquitoes. Other methods of mosquito control such as source reduction and aggressive larviciding should be
considered first. 

How Efficient are Mosquito Adulticides?

In a joint statement on mosquito spraying, the CDC and EPA state that in order to be effective, spraying must be done under extremely precise conditions: at the ideal temperature, with low winds, at the time of day when mosquitoes are most active, and with carefully calibrated equipment to form droplets the right size. Furthermore, the spray is only effective against adult mosquitoes and not eggs or larvae. In an April 2001 report, the CDC stated, ”Adulticiding, the application of chemicals to kill adult mosquitoes by ground or aerial applications, is usually the least effective mosquito control technique” and also “the most effective and economical way to control mosquitoes is by larval source reduction.” The EPA and CDC advocate Integrated Pest Management (IPM). They explain, “IPM is an ecologically based strategy that relies heavily on natural mortality factors and seeks out control tactics that are compatible with or disrupt these factors as little as possible. IPM uses pesticide, but only after systematic monitoring of pest populations indicates a need. Ideally, an IPM program considers all available control actions and evaluates the interaction among various control practices, cultural practices, and weather and habitat structure. This approach thus uses a combination of resource management techniques to control mosquito populations with decisions based on surveillance”.

 

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