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Adult Mosquito Control

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Adulticides - Chemicals used to control adult mosquitoes are called Adulticides.

Truck mounted ULV (Ultra Low Volume) foggers are used to apply these adulticides. Typically less than 1 ounce of active ingredient is applied per acre.

Mosquito fogging is usually done in the evenings after sunset when mosquitoes are most active. Occasionally, some early morning fogging may occur and will take place before the sun rises.

The Glenn County Mosquito & Vector Control District (GCMVCD) does NOT fog during daylight hours for three reasons:

  • Presence/activity of pollinators (honey bees), and other beneficial insects.
  • UV light rapidly breaks down the Adulticide products we use potentially causing sub lethal doses resulting in the build up of chemical resistance in local mosquito populations. 
  • Lack of desirable weather conditions, fogging requires an atmospheric inversion to keep the Adulticide products down so that they can drift and we can achieve the greatest efficacy of each Adulticide product.

The GCMVCD does NOT fog areas that:

  • Bee Hives are present.
  • Registered Organic with the Glenn County AG Department or are posted Organic.

If you have Bee Hives or Organic Property PLEASE make sure to contact the GCMVCD and verify we have your location on file and make sure all Organic Property is well posted.


The GCMVCD works with the Center for Vector-Borne Disease Research (CVBDR) at the University of California Davis to test adult mosquitoes trapped in Glenn County to make sure that the wild mosquito populations is not building up a tolerance to the chemicals that we are applying. The mosquitoes are tested against the chemicals that the GCMVCD uses the most to ensure that they still have good efficacy and that the mosquitoes are not becoming resistant to the active ingredients in the chemicals. To help prevent the mosquitoes from building up a tolerance, every few years the GCMVCD rotates the chemicals it uses always making sure to switch up the active ingredients.