Mosquito population surges in Iowa after rainy summer

DUBUQUE, Iowa (KCRG) - Iowa is seeing an increase in mosquitoes following a wet summer.

“As we got into some of the larger rainfall in late June, some of our mosquito populations really exploded,” said Iowa State University associate professor Dr. Ryan Smith, noting standing puddles and flood water create the ideal breeding ground for mosquitoes.

Smith leads the state’s Mosquito Surveillance Program, overseeing about 100 traps statewide. He said the majority of the nearly 60 species of mosquitoes detected in Iowa don’t carry the West Nile virus or Eastern Equine Encephalitis, also known as Triple E, which are prompting warnings in the Northeastern United States.

“Even if these other mosquito species come into contact with the virus, they can’t successfully transmit it,” explained Smith. “The Culex species have somewhat evolved to drive the progression of this disease. A lot of that is because of their propensity to feed on birds, which this virus tends to amplify and reside in bird populations.”

The Culex species have been detected in central and western Iowa, including in Harrison County, where the Iowa Department of Health and Human Services confirmed the West Nile virus infected an older adult last month.

The case marked the first confirmed infection in Iowa in 2024.

“What we’ve seen in the past is that these are really the primary mosquito species responsible for West Nile virus transmission,” said Smith. “Their increase in abundance, seeing above average activity levels, I think does raise a bit more of a risk or concern for those in the state.”

While most people who come into contact with the West Nile virus won’t experience symptoms, Smith noted it can cause severe flu-like symptoms.

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