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Types of Vector Control


The purpose of the Williston Vector Control District (WVCD) is to manage mosquito populations in and around the major population centers of Williams County, excluding Tioga as they have their own Vector Control District. WVCD conducts both aerial and truck mounted spraying operations during the summer months.

Williston Vector Control routinely operates truck mounted sprayers which can apply ground based larvicide and adulticide treatments. Aerial treatments are conducted by contracted certified aerial applicators. Annual aerial larvicide and adulticide missions are also conducted in collaboration with the U.S. Air Force Reserve based out of Youngstown, Ohio.

Multiple factors are taken into consideration when deciding if, and when a treatment will occur. Williston Vector Control staff routinely collect mosquito samples five days a week from traps located throughout Williams county. An increasing mosquito population coupled with favorable weather conditions inform the decision of whether or not a treatment is necessary.


Larvicides refer to pesticide products used to prevent the larval mosquito population from growing into biting adults. Williston Vector Control uses a variety of ecologically-friendly larvicides like B.t.i (Bacillus thuringiensis israelensis).


Adulticides refer to pesticide products used to manage adult mosquito outbreaks. Williston Vector Control uses EPA-approved products for use in ultra-low volume (ULV) applications of adulticides. Currently, only the product Zenivex (active ingredient: etofenprox) is used.

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