The Manatee County Mosquito Control District prefers the use of larvicides (over adulticides) as our front-line mosquito control approach. This technique targets the aquatic stages of mosquitoes while they are still concentrated, immobile and highly susceptible. We use trucks to spray roadside ditches and low-areas where mosquitoes breed before they can emerge as adults. Sometimes we can not access some mosquito breeding areas with trucks so the public may occasionally see our staff using backpacks or handheld sprayers.
We also utilize our helicopters for larvicide applications over larger, remote wetland habitats. These missions occur in the daytime (unlike night missions for spraying adult mosquitoes) and typically apply a granular bacterial larvicide that falls directly under the spray pattern of the aircraft (no significant “drift” as is desired and observed with adulticide spraying). On rare occasion we sometimes spray with liquid larvicides in “open” habitats when large raindrop sized droplets can reach the target below. And we occasionally use other EPA-approved larvicides such as methoprene when appropriate or field conditions dictate an alternative to Bti.
The "freshwater" mosquitoes found in the eastern part of the county are not easily controlled through these larviciding methods. They are not typically concentrated in clearly definable areas or are in areas too vast to be effectively treated in the limited time available (3-4 days).