Larviciding is the control of mosquitoes in their larval stages of life in aquatic habitats and is achieved through ground, aerial, and hand applications of larvicides.  Larvicides are natural agents or chemical products that are specifically designed to kill mosquito larvae and are typically more effective than adulticiding, but less so than source reduction. IRMCD’s larviciding program focuses on salt marsh wetlands along the Indian River Lagoon.  Approximately 2000 acres of these wetlands are "impounded" (kept flooded for part of the year) and managed. The remaining salt marsh wetlands and adjacent areas that produce mosquitoes require frequent larviciding treatments.

Our salt marshes can produce millions of mosquitoes per acre on each flooding event during the summer. At times, the water seems alive with mosquito "wigglers" lurking just below the surface. It is far more effective to control mosquitoes when they are still concentrated in the marshes than to try after they mature and fly off in every direction. Also, due to poor ground access and EPA restrictions on where we can use our spray trucks, sometimes the only time to attack the mosquitoes is when they are in their larval stages.

The IRMCD employs field inspectors who spend their days visiting hundreds of known mosquito-producing areas and checking the water for the presence of larvae. Inspection and treatment information is recorded in a computerized database. Regulations require us to document that mosquitoes are occurring in a marsh to justify treating them. 

If the affected area is small, the inspectors usually apply an appropriate larvicide immediately to kill the mosquitoes. When large areas need larval treatment, a local flying service (T.R. Summersill Inc., Belle Glade, FL) is contracted to make these applications with fixed-wing aircraft. In some limited areas, slow-release granular formulations are used to provide long-term control of saltmarsh mosquitoes.