Below is the summary of recent mosquito activity in Iowa from the ISU Medical Entomology Laboratory. Mosquito surveillance data can be viewed online at www.mosquito.ent.iastate.edu
After last week's spike of floodwater mosquitoes, the numbers of Aedes mosquitoes are again on the decline around Iowa. See the chart below.
We're unsure how much impact the recent heavy rainfall will have on populations in the coming weeks. Summer is still in session and we could still see significant hatches of floodwater mosquitoes. For example, some of you may recall that flooding in August of 2007 resulted in mosquito explosions in September of that year. However, if autumn gains an early stronghold on us in the next month, or even if some of these recently chilly nights continue, the populations of floodwater species will continue to decline.
What we do know is that populations of Culex mosquitoes are stable and harboring West Nile virus right now. Our first sample of mosquitoes that tested positive for WNV was collected this week in Des Moines. It is surprising that in a bustling mosquito year, like this one, positive samples are fewer and farther between than in a year like 2012, when we were hard pressed to find standing water in Iowa yet detected 40 WNV-positive mosquito samples. The dynamics of mosquito populations are complex, and the work done by all of us helps to shed light on the situation.
Aedes vexans is still the most abundant mosquito in the land (and water). However, our other two major floodwater species are on the wing - Ae. trivittatus and Ae. sticticus. Other nuisance species common right now are Ae. sollicitans, Anopheles punctipennis, An. quadrimaculatus, Psorophora ciliata (the huge, stripe-legged mosquito that many of you know), Ps. horrida (so-named because of its horrid bite, which is an exaggeration), and Coquillettidia perturbans (the common sawtail mosquito, so-named because of the way that larvae saw into underwater plant tissue to breathe). Needless to say, mosquito diversity is impressive in a late summer in Iowa!
To see and learn more about these mosquitoes check the mosquito pages on BugGuide.
At this time of year, it's as important as ever to remind you to be aware of places where water may accumulate on your properties and act as breeding habitat for mosquito vectors. A mere bucket in your backyard could be the source of a Culex mosquito that is infected with West Nile virus. "Source reduction," as we call it, also translates to a reduction in human-mosquito interactions.
Mosquito populations in Iowa for the current and previous year as of August 21, 2015 according to New Jersey light trap records. Data are shown as a weekly average of traps running.
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