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ADULTICIDING PROGRAM
Adulticiding (ground spraying) is the most visible component of a comprehensive mosquito control program. Adulticiding is the reduction of the numbers of adult mosquitoes by applying a fog of insecticide throughout the city by the use of ground spraying.
During the summer months, the mosquito control program usually ground sprays ten to fifteen times at a cost of $4,000 per application. The ground spraying is done when the mosquito counts exceed the 100 average count in mosquito traps located throughout the City of Grand Forks.
The insecticides used are synthetic pyrethroids. These products are labeled safe to use in residential areas for adult mosquito control by certified personnel. These synthetic pyrethroids are biodegradable in sunlight, which minimizes any hazards to our environment from the ground spraying.
Mosquitoes are a predictable insect. It seems that when we get heavy rainfall and warm temperatures we get a bumper crop of mosquitoes. The reduced numbers of mosquitoes, although there are still plenty to be a nuisance, can be attributed to an active larviciding program. The ground spraying further reduces the number of mosquitoes to a tolerable level.
Citizens sometimes ask why we have to ground spray multiple times during consecutive weeks before we finally reduced the number of adult mosquitoes in the City of Grand Forks to a tolerable level?
The explanation of the frequent ground spraying includes several variables. The species of mosquito we are dealing with is the Aedes Vexans. This particular mosquito has a natural life span of four to six weeks. It is noted that this mosquito will migrate from its hatching site up to twenty miles or more to obtain a blood meal. The mosquito is a relatively fragile insect that prefers to fly about when winds are less than 10 mph. The City of Grand Forks does attract a large number of mosquitoes that migrate in from outside our larviciding area.
After a substantial rainfall the mosquito population builds in large numbers and can increase up to 10-fold over night and build for a period of 10 to 15 days before the numbers began to-level off. Our ground spraying efforts occurred at the beginning, middle, and the end of this cycle which accounts for the quick increases and decreases in the mosquito population. The ground spray that took place about seven days later - primarily due to the migration of mosquitoes from outside the Grand Forks area. The basis for this conclusion is the relatively slow rise in mosquito numbers during that week prior to the ground spray and the steady decline in numbers after the ground spray. The other factor is that most of the rain received in July, dried up in the first two weeks of August, thereby reducing the mosquito habitat sites and not producing more mosquitoes. |