Adulticiding is the final component of Integrated Pest Management. Although every effort is taken to eliminate mosquito larvae before they become adults, various factors make it impossible to eliminate every mosquito. Therefore, adult mosquitoes emerge from breeding sites or migrate into Cass County in search of a meal or a mate.
Mosquitoes in the adult stage can be controlled while resting or flying. Our decision to initiate an application to control adult mosquitoes is based on surveillance results, inspections by field aides, sweep counts, and nuisance mosquito calls. Backpack sprayers are used to treat vegetation where adults rest during the day. This type of treatment is applied to residential areas, parks, and playing fields. The mist put out by a backpack is controlled and can be applied to areas where it will not harm humans or pets.
In the evening, mosquitoes come out of hiding, making them susceptible to control materials applied by truck mounted foggers. These applications typically occur a few hours before and after twilight. This period is when adult mosquitoes are most abundantly feeding and active.
Cass County has 17 truck mounted foggers that are calibrated to apply ultra low volume(ULV) spray. Our ULV trucks put out droplets around 20 microns in diameter or 0.0008 inches across (about the width of a living cell). These droplets are in the air for about half an hour and travel up to 300ft. Cass County Vector Control currently uses an application rate of approximately 0.0035 lbs per acre of permethrin, or about 0.4 grams of active ingredient per "average" household yard. In contrast, application rates for certain agricultural products such as apples can be up to 0.4 lbs of permethrin per acre of crop (181 grams per acre). For information, product labels, and MSDS for all adulticides used by Cass County: Products
There are several reasons that we may not spray during the scheduled time and date:
1. No Spray Zones - areas where people have requested no spraying due to health concerns or other reasons.
2. Bodies of water - By law, adulticiding is not allowed near certain bodies of water due to potential environmental contamination.
3. Inclement weather - Label instructions specify that treatments not be made in winds over 10mph or less than 1mph and/or temperatures below 58 degrees.
SPRAY TRUCK HOURS OF OPERATION
Depending upon time of year and degree of infestation, spray trucks are scheduled to operate between dusk and dawn. Typical mosquito season spray hours are between 7 p.m. and midnight .
Spraying Schedule