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What is Adulticiding?

Spraying or adulticiding is the application or treatment of pesticides to exterminate adult mosquitoes. The most common way to apply these pesticides is using truck-mounted ultra-low volume spray units driven on public roadways.  Adulticiding is one of the tools we have in order to control and manage mosquito populations. When done properly, adulticiding is an effective way to reduce the numbers of mosquitoes and reduce people's risk of contracting mosquito-borne diseases.

When Do We Apply Adulticide?

It is important to apply these pesticides when mosquitoes are most active. For the species that carry West Nile virus, it is best to apply adulticide just before sunset or within the next several hours that follow. Licensed and trained staff apply adulticide intended specifically for mosquito control. The pesticides are registered with the U.S. EPA and Ohio Department of Agriculture, and are applied according to federal and state laws.

How Do We Apply Adulticide?

Franklin County Public Health uses ultra-low-volume (ULV) spray machines that are computer controlled, GIS equipped and calibrated to apply extremely small amounts of adulticide over large areas. The droplet size of the pesticide applied in the spray is small enough to be lethal to mosquitoes, but will not adversely affect other insects. The adulticide applied by our truck mounted units do not persist in the environment for very long; they naturally break down within hours, will decompose as they are exposed to air, and are destroyed rapidly by sun light. The morning after an application, the amount of residual adulticide on exterior surfaces will be negligible.

When Do We Decide to Adulticide?

The decision to adulticide is based on multiple factors. We consider the following information:

  • Is there a significant increase in the number of mosquitoes that can carry disease in our weekly trap locations?
  • Is there a lab-confirmed or RAMP tested presence of West Nile virus (WNV) in the mosquitoes we trapped?
  • Is there a history of WNV in an area?
  • Are weather events or weather patterns contributing to an increase in mosquito populations?
  • Has there been a confirmed human case of WNV or other mosquito-borne diseases?
  • Are attempts to control mosquito populations through larviciding not been effective?
  • Or, there is a public health emergency as determined by the Board of Health and/or Health Commissioner.

Once we consider these factors, we provide our recommendations to the officials of the local jurisdiction for which we intend to spray. These local jurisdictions determine if and when to spray.

In addition, the evening following our spraying, mosquito traps are set in the areas we sprayed to determine if the adult mosquito population was adequately reduced from our previous week’s trap. We look for a 60% reduction in adult mosquito population. If we have not achieved near that 60% reduction, we may consider spraying that area again. We also continue to look for and eliminate sources of breeding in these areas that may be contributing to the high trap counts.

If you do not want your property sprayed, please see our Do Not Spray registry information and form.

Barrier Treatments

With the summer months comes festivals, fireworks, movie nights, and other outdoor events. To help everyone better enjoy these events we provide barrier treatments for these city, village or township activities in addition to typical adulticiding. In a barrier treatment, chemical is sprayed on the foliage surrounding an open area such as a park or fairground. The chemical is designed to cling to leaves. As mosquitoes land on the treated areas, they are killed. Under ideal conditions, this treatment can last a week or more.

A Complete List of Adulticides We Use

KONTROL 4-4 (EPA Reg. No. 73748-4)

MasterLine® Kontrol™ 4-4 for Mosquitoes, Flies, and Gnats is a 4.6% permethrin/4.6% PBO low odor oil formulation.  As a non-corrosive, it won't damage cars, trucks or airplanes.  Its broad spectrum, superior formulation is clean and clear and provide quick knockdown of most mosquito species as well as other Diptera species such as biting and non-biting midges, black flies and gnats.  With no EPA required water set back, Kontrol 4-4 can be applied ultra-low volume (ULV) by air or ground. It can also be applied either as a mist barrier or from a thermal fogger.
Product Label | MSDS  

PERMANONE 4-8 (EPA Reg. No. 432-1277)

PERMANONE® is an oil based ULV product for safe and effective control of mosquitoes. PERMANONE exceeds all minimum requirements for scientifically based mosquito control programs. PERMANONE is a permethrin based product that is the most widely used chemical family in domestic mosquito control. The PERMANONE product group is considered to be a more environmentally friendly alternative without the unpleasant odors, corrosiveness, and paint damage associated with organophosphate products.
Product Label | MSDS

SUSPEND SC (EPA Reg. No. 432-763)

SUSPEND SC insecticide is a suspended concentrate insecticide containing 0.42 lb active ingredient per gallon. SUSPEND SC insecticide is designed for use both indoors and outdoors and will provide effective knockdown and long residual control of a wide variety of pests. Each application will provide a parameter barrier treatment to prohibit pests from entering the treated surface. Franklin County Public Health does not use this product in its truck-mounted sprayers, but would only apply this to foliage and vegetation in specific residential and public settings in order to obtain long-term residual control.  This product is not applied to flowering plants, crops or areas where pollinators would be found.
Product Label | MSDS