Evaluating Adult Mosquito Control Treatments

It’s important for the District to know whether the adult mosquito control treatments we conduct have the intended effect: an immediate reduction in the number of WNV-infected adult mosquitoes in an area.

To ensure that our adult mosquito control treatment was effective, we compare the number of mosquitoes trapped in the immediate area prior to treatment to the number of mosquitoes trapped in the same area after the treatment. This is reported as an overall reduction in the mosquito population.

We also test the effectiveness of the product used for the adult mosquito control treatment by placing cages of laboratory-raised mosquitoes in the area to be treated. After the treatment, we pick up the cages and count the number of mosquitoes surviving. This tells us if the product works well on the mosquitoes in that particular area.

After the treatment, we test mosquitoes trapped in the area to ensure that no WNV-infected adult mosquitoes remain. This ensures that the immediate human health risk has been eliminated, and it is safe to return to conducing preventative treatments for mosquito larvae.