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It's biting time: Pest season is in full swing

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staff, Gazette
June 6, 2013

— With warm weather finally returning to Wisconsin, summer pest season also is entering full swing.

And that means critters that not only irritate but also pose potential health risks.

According to Phillip Pellitteri, a UW-Madison entomologist, this year's mosquito season is set to be much more active than last year as a result of flooding from heavy rains. Pellitteri said while the tick population statewide has been in decline in recent years, there is a higher incidence of Lyme disease among deer ticks.

Pellitteri said last year's drought caused the mosquito season to start earlier and also resulted in an "unusually pleasant" summer with far fewer of the insects during the season.

But more mosquitoes does not necessarily mean higher rates of West Nile virus because the disease is more dependent on human causes, such as polluted swimming pools or birdbaths, he said.

Pellitteri also noted this year's warmer winter is not to blame for the heavy mosquito season because the insects' short life cycles mean one particularly strong weather front—such as very heavy rainfall statewide between January and May—can significantly impact their numbers for the year.

In contrast, Pellitteri said while there are fewer ticks roaming the woods, there is an increasing trend of deer ticks moving farther into southeastern Wisconsin. There also is a higher number of these ticks capable of transmitting the disease to humans, with about 40 percent of the adult population carrying the disease, he said.

Though both deer and wood ticks are common in Wisconsin and can pass various diseases on to humans, only the deer tick, which appears much smaller than the wood tick, carries Lyme. Pellitteri said deer ticks must be embedded in the skin for at least 24 to 48 hours for Lyme disease to be transmitted.

According to Department of Health Services data, there has been a steady increase in instances of Lyme disease in the state since 1990, with more than 2,400 confirmed cases reported in 2011.

Tim Banwell, Rock County Health Department environmental health director, said 33 caseswere reported in the county in 2012, with 13 confirmed.

Pellitteri said the high rate of Lyme infection among deer ticks puts Wisconsin well above the Center for Disease Control's new benchmark for receiving a one-day antibiotic treatment if a resident finds a deer tick that has been embedded for at least 36 hours.

"The bottom line is they (ticks) are going to be out there, and if you're going to be in their living room you better take precautions," he said.

As far as the state's other common seasonal pests, Pellitteri said Japanese beetles could arrive slightly later than usual this year. He also said the population likely will be lower in Rock County because populations typically decline after about a decade of high prevalence in a new area.

Earwigs, an insect that thrives in lush conditions, should start arriving "any day now," he said.

Banwell urged residents to take precautions to prevent being infected with diseases carried by insects during the summer months.

Because only 50 percent to 70 percent of those with Lyme disease exhibit the telltale bull's-eye-shaped rash, he said people who have been exposed to deer ticks and begin to feel flu-like symptoms should see a doctor.

"It's an important public health issue, and people should know what precautions to take to reduce their risk of getting diseases," Banwell said.



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