Ditching those uninvited guests

It wouldn't be summertime without backyard barbecues, but the one-two punch of a mild winter and an unusually wet spring means residents of the western suburbs are entertaining some unwelcome guests -- swarms of hungry mosquitoes.

Fed-up residents are complaining about the pests to local public health and mosquito control officials, who say the problem is worse than usual.

``I'm really concerned that there's going to be a lot of pesky mosquitoes out there this year," said Hopkinton's public health administrator, Thomas Ryder, who reports fielding two or three complaints a day. ``They say, `I was just outside, and they're biting like crazy. Is there anything that can be done?' "

The bugs are an itchy annoyance, but they also raise concerns because of diseases they may carry. Mosquitoes bearing the West Nile virus, potentially deadly for humans, were detected in the area a month earlier than usual, meaning they have more time to infect someone before cold weather puts an end to the threat.

Timothy Deschamps' job is to keep the bloodsuckers in check. As executive director of the Central Massachusetts Mosquito Control Project in Northborough, he's in charge of fighting the insects in 36 area cities and towns, including many of the western suburbs.

``We try to respond to complaints within the week, but with the backlog it can take one to two weeks at a maximum," Deschamps said.

Area residents plagued by mosquitoes have flooded the state agency with more than 100 calls and e-mails a day. Its force of 17 full-time technicians and 11 spraying trucks can respond to about 200 problem areas on a good day, Deschamps said.

The agency also monitors the area's mosquito population, looking to gauge this year's cohort and checking to see if they're carrying diseases.

``We will have tens of thousands of mosquitoes tested this year at the state lab," Deschamps said. ``If we're lucky, we won't have any test positive for viruses. Last year, we did have about a dozen test positive."

Mosquitoes trapped in Holliston and Westborough last year were found to be infected with another troublesome insect-borne disease, Eastern equine encephalitis, while a mosquito from Westborough tested positive for the West Nile virus, he said.

Mosquitoes trapped in Needham last month were found to be infected with West Nile. While no human cases have been reported in area communities this season, the early arrival of the viruses has raised concern among officials.

``Last year, our first positive wasn't until late July," said Dr. Bela Matyas of the state Department of Public Health. ``Obviously, the fact that it's a month earlier this year means we have a month longer of potential risk of infection, but this isn't the earliest we've seen it."

David Henley, who manages the Waltham-based East Middlesex Mosquito Control Project, said counts ``are up, and that's no surprise," considering the soaking spring and early summer rains that created ideal conditions for mosquito species that hatch in forested wetlands. To make matters worse, the pests are being joined by a species of marsh mosquito that isn't dependent on rain, Henley said.

``In some traps, we're seeing numbers like 1,000 to 2,000 mosquitoes," he said. ``That's high."

Home insecticide sprays can work on a small scale, but they fall short of providing a mosquito-free environment, as do propane-fueled mosquito traps that lure the bugs with carbon dioxide that resembles people's breaths, experts say.

``If you are sitting upwind from the trap, it's probably preventing some mosquitoes from getting to you," Henley said. ``If you move to the right or the left of that narrow plume of carbon dioxide it's putting out, a mosquito could just come by and get you without ever noticing the trap."

Insecticide sprays will wipe out the mosquitoes in your yard, he said, but unless you spray a couple of times a day, other mosquitoes eventually will move in.

Christen Olson of Holliston coats her four children with DEET-containing bug spray before letting them play outside her Norfolk Street home, which borders a marshy woods.

She worries about West Nile virus after one of her boys got Lyme disease from a tick bite last summer.

``It's so bad out back, I don't let them go back there this time of year," Olson said recently as she planted flowers at dusk. ``I try to get them in from the pool by this time. We'll get eaten up out back."

Holliston's health agent, Ann McCobb, said her office hadn't gotten many complaints recently, likely because most residents call the mosquito control agency directly.

``I'm doing what we advise everyone to do, which is avoid being outside at dawn and dusk and to wear long sleeves to protect yourself. Prevention is key," McCobb said.

Deschamps said his staff is trying to spray neighborhoods in each of his agency's communities at least once a week.

But the resmethrin spray, which Deschamps described as a synthetic copy of an insecticide occurring naturally in plants, wears off by the next morning, if not sooner, he said.

``It varies according to the weather conditions, but we can knock the mosquitoes down enough for residents to have some relief," he said. ``We use a very small amount, and the product has a very low toxicity."