Below is the summary of mosquito activity in Iowa from the ISU Medical Entomology Laboratory. During the summer months, the Iowa State University Medical Entomology Laboratory monitors mosquito populations and mosquito-borne diseases in Iowa. Mosquito collection data can be viewed online at the Iowa Mosquito Net
As you can see from the chart below Iowa mosquitoes are becoming less and less abundant each week since the floodwater mosquito populations exploded in early July (week 28). As long as the perfect storm of rainfall and temperature does not hit us again, we may be in the clear as we cruise into fall. Here's hoping!
The scarcity of floodwater mosquitoes in late summer is something that we see in most years; an exception was 2007, when flash flooding in Cedar Rapids and elsewhere in August caused a grand resurgence of floodwater mosquitoes.
Although the floodwater mosquito populations have crashed by now, this is the time that the filth breeders, which will lay eggs in any water-holding container they can find, persist in moderate abundance and can even increase significantly. As a result of these factors, the filth breeders traditionally have a higher proportional abundance in Iowa in late summer and early fall. This is important to us because these species (Culex species) happen to be our most important vectors of West Nile virus. The fact that WNV "season" in Iowa strongly matches the time frame for Culex abundance is not just coincidence; if the vectors become far more abundant, the virus can have a higher rate of transmission. We just received notification of 4 more mosquito pools testing positive for WNV in August - 3 in Ames and 1 in Sioux City.
Therefore, right now is the time to maintain good mosquito control practices. Get rid of standing water containers (buckets, tires, bird baths, barrels, turned over truck toppers, etc.) to reduce the amount of habitat available to mosquito larvae, and use insect repellent to keep adults at bay. Just because you don't notice mosquitoes as much in the environment right now does not mean that they are less of a concern.
Mosquito trap catch data from the ISU Medical Entomology Laboratory, August 22, 2014.