More bugs bugging the Fox Valley

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Updated: November 25, 2011 12:23AM

This summer’s thunderstorms left many throughout the Fox Valley without power. They downed trees and flooded basements.

They also left standing water across the area, breeding grounds for the mosquitoes that carry the West Nile virus.

Earlier this month, mosquitoes trapped on the east side of Aurora became the first in Kane County to test positive for West Nile.

That comes as the McHenry County Department of Health has reported an uptick in the number of cases of Lyme disease this summer in the county. The disease can be carried by black-legged or deer ticks, the department said.

“There are so many things that affect insect populations — it’s just crazy,” said Devin Krafka, a research assistant in the entomology department at the Morton Arboretum in Lisle.

“I would say the weather has an effect on all the bugs.”

Mosquitoes

The mosquitoes trapped in Aurora make Kane the 12th county in Illinois where West Nile has been reported this year in mosquitoes, birds or horses, according to the Illinois Department of Public Health. A batch of mosquitoes in Oswego in late June was the first in northern Illinois to show signs of the virus this year.

So far, no cases have been reported in humans, according to the Illinois Department of Public Health.

“That is somewhat unusual,” said Tom Schlueter, spokesperson for the Kane County Health Department.

Last year, five cases of West Nile were reported in people in Kane County alone.

The virus is transmitted through the bite of a culex mosquito that has picked up the virus by feeding on an infected bird. Most people with the virus show no symptoms of illness, although it may lead to encephalitis or meningitis in the most serious instances.

The other kind of mosquito found in Illinois — Aedes vexans — are the “floodwater mosquitoes,” according to Laura McGowan, a spokesperson for Clarke, a mosquito control company based in Roselle. Although they have not been significant disease carriers in Illinois, those mosquitoes are “nasty biters,” she said.

Last year was a “pretty heavy mosquito season,” and this year is tracking evenly with it regarding the number of mosquitoes Clarke has trapped, McGowan said. In a trap in which Clarke usually would find about 150 mosquitoes, it now is finding thousands, she said.

But the continuous rain has been a “double-edged sword” for the West Nile-carrying culex mosquitoes, according to Schlueter.

On one hand, the falling rain has stirred up any standing water, which dissuades culex mosquitoes, he said.

Left undisturbed for several days, however, the standing water left behind after a rainstorm is where the culex lay their eggs, he said. It takes about a week to 10 days for eggs laid there to hatch, McGowan added.

Clarke has a “whole toolbox” of ways to control the mosquito population and contracts with many communities in the area, including Elgin, McGowan said. It can conduct surveillance, mapping the insects’ nesting areas; treat standing water with larvicide to keep mosquito eggs from hatching there; and spray a mosquito barrier treatment to kill adult mosquitoes in an area.

And there are simple things people can do to control the number of mosquitoes in their own backyard and lessen their chances of being bitten, she said. People can wear insect repellents with DEET when outside, clear their roof’s gutters and check for standing water in birdbaths, baby pools or ditches, she said.

Ticks

The McHenry County Department of Health also is warning residents to take precautions against tick bites during the warm August and September months to prevent contracting Lyme disease.

Thirteen cases of Lyme disease have been reported in McHenry County this year, according to the department. Of those, six people had been bitten by black-legged or deer ticks in the county.

That’s a jump from six total cases of the disease in the same time period last year, according to the department.

But county health department spokesperson Debra Quackenbush said, “At this time of year, this is not unusual for us.”

Only two cases of Lyme disease have been reported this year in Kane County, Schlueter said. And that’s a number that fluctuates: 10 were reported last year, 13 the year before that and seven in 2008, he said.

“The real message is one of education,” Quackenbush said.

Lyme disease typically manifests itself three to 30 days after a person has been bitten by an infected tick. Symptoms vary from fatigue, chills and fever, headache and muscle and joint pain to swollen lymph nodes and a skin rash. Most cases can be treated with a few weeks of antibiotics.

Ticks live in and near wooded areas, tall grass and brush. And as with mosquitoes, there are things you can do to prevent being bitten by the insects.

Outside, people should walk in the center of trails and wear insect repellents with DEET to avoid picking up a tick, according to the McHenry County Department of Health. Once inside, bathe or shower as soon as possible to wash off and more easily find ticks. Check especially under the arms, in and around the ears, behind the knees, inside the belly button, between the legs, around the waist and in the hair.

Fireflies

On the bright side, the number of fireflies in the area has been on the rise over the past five years, according to the arboretum’s Krafka.

If people haven’t seen them lighting up the night sky this summer, she said, “there are lots and lots of things that affect the lightning bug population.”

Female fireflies spend their time on the ground, where they lay eggs, so they are affected any time the groundcover is disturbed, such as when land is paved for a parking lot, she said. And male fireflies glow to signal the females below — so more light, such as from houses, can affect them.

Krafka also pointed to the popular summer pastime of catching the insects in jars.

“People go out and collect a bunch of lightning bugs and don’t realize the population is in a downturn,” she said.

That population, while trending upward, fluctuates year to year, as with other insects.

If there are a lot of mosquitoes this year because of the rainwater, their predators — birds, bats and dragonflies — will thrive, she said. If there are a lot of predators, then next year there may not be enough insects to sustain them all.

“It’s a constant cycle and a constant battle,” Krafka said.

“But I definitely would say the rain is the thing that makes the mosquito population increase.”