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Swarms of Ochlerotatus triseriatus have been invading neighborhoods after a rainstorm last month created prime conditions for their nurturing. They're annoying but aren't a vector for West Nile.

Mosquitoes Out in Record-breaking Numbers This Year

By Andy McKeeveriBerkshires Staff
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Culex pipiens is a known carrier for West Nile and other diseases. 
PITTSFIELD, Mass. — It is going to be a record year for the local mosquito population in Berkshire County.
 
And residents have taken note. Over the last week, the Health Department the Berkshire County Mosquito Control Project had fielded hundreds of calls from residents about high population numbers. 
 
"This is going to be the biggest year in history. We are at record West Nile already," Mosquito Control Project Christopher Horton said.
 
West Nile was confirmed Thursday in another sampling of mosquitos in the area, raising the number of positive samples to 20 in recent weeks. While no human in Berkshire County has tested positive, there have been nine human and two animal cases in the state.
 
It is approaching peak mosquito season and the population has been particularly high right now because of flooding in mid-August. Horton said a rainstorm on Aug. 18 caused the Housatonic River to overflow into the floodplain from Pittsfield all the way to the Connecticut border. While it had only lasted two days, that was long enough to start the development of eggs of the floodplain-born Ochlerotatus triseriatus species.
 
"All of those eggs started development at once. We're talking hundreds of acres," Horton said. 
 
About a week later, thousands upon thousands of mosquitoes rose from the riverbanks and by a week after that, they've migrated into neighborhoods to feast. 
 
"They are getting into the neighborhoods. We want to keep them as isolated as possible," Horton said. "The longer we wait, the more they'll move."
 
In the last few years, the county hadn't seen much of the floodplain species because there hadn't been a flooding event. Health Director Gina Armstrong said the Ochlerotatus triseriatus is not quite known for carrying West Nile virus and the state typically doesn't test those for the virus. But, they are known the be a nuisance. 
 
The state does, however, does test the Culex pipiens species for West Nile and more of those have been carrying the virus than in years past. So far, 20 mosquitoes tested positive for the disease, five of which were confirmed earlier this week, in Pittsfield alone. 
 
"DPH reported it is double the virus than normal," Armstrong said. 
 
Horton said the population of Culex has actually been lower than in years past. But, the percentage of those carrying the disease has taken a dramatic increase due to more and more birds carrying West Nile virus. 
 
"These numbers have been fairly low but even though the numbers are low, the disease findings have been high," Horton said. 
 
Countywide a total of 50 mosquitoes were confirmed with the virus The project collects samples in just 10 Berkshire towns and those samples are tested by the state. Across the state, there have been nine human cases and two animal cases -- though there have been none of either in Berkshire County. 
 
About 20 percent of infected people will have symptoms such as fever, headache, body aches, nausea, vomiting, swollen lymph glands, skin rash on chest, stomach and back. One percent of infected people will develop severe illness but the majority of people who are infected will not have symptoms. 
 
Armstrong said with the nine people identified across the state, those have been serious cases leading the individual to be in the hospital. 
 
The 20 findings in Pittsfield is dramatically different from 2016, when there were only two findings of West Nile and in 2014 when there was only one. 
 
"This is definitely the highest we had since 2012 when we had 11 positive findings," Armstrong said.
 
With a greater presence and a greater number of mosquitoes, the Health Department and the Berkshire Mosquito Control Project are concerned about the possible spread of West Nile Virus. In response to the consistent presence of the disease, the project deploys a truck-mounted adulticide spraying to kill off adult mosquitoes. 
 
On multiple occasions and locations throughout the summer, the spraying has been deployed and Pittsfield will have three more scheduled this upcoming week -- two of which in locations already sprayed on multiple occasions this year -- and Sheffield will also be sprayed, where two more positive samples were collected.
 
"Some people are critical of the truck-mounted spraying but it is effective," Horton said, estimating that the population in an area being sprayed drops by about 80 percent.
 
Indeed there has been much criticism of the adulticide sprayings. For multiple years in a row, residents have petitioned and pushed for the city of Pittsfield to leave the project. Those in opposition counter Horton's claims of effectiveness and say the chemicals are detrimental to human health and the environment. 
 
The Mosquito Control Project says the adulticide spray is low toxicity and quickly breaks down as to not leave any residue but those in opposition don't buy it. Those in opposition say it is bad for the ecosystem, bad for humans, and doesn't work. The majority of towns in Berkshire County aren't part of the project and opponents note that there has not been a widespread disease issue.
 
Opponents first tried to go to the Board of Health to ask for changes and then petitioned the City Council. A few years back an ad-hoc committee was formed to develop a different strategy to control the mosquito population but the recommendations were never taken up in earnest.
 
City and health officials still say the amount of adulticide being used is small and that the chemicals have been approved by the U.S. Environmental Protection Agency. Health officials say protecting against a possible widespread outbreak of West Nile with the spray is worth it.
 
"The number of mosquitoes in the city is also increasing the risk," Armstrong said.
 
The city has consistently provided residents with the same advice: When outdoors, wear long pants, a long-sleeved shirt and socks; Use a repellent with DEET according to the instructions on the product label; keep mosquitoes out of your house by repairing holes in screens and making sure screens fit tightly to doors and windows; schedule outdoor events to avoid the hours between dusk and dawn when mosquitoes are most active; Remove areas of standing water around your home to eliminate sources of mosquito breeding.
 
Armstrong emphasized the importance of residents to continue taking precautions in September when the most cases of diseases are reported.
 
After the most recent discovery of West Nile in a mosquito, a truck-mounted mosquito spray application is scheduled for Tuesday, Sept. 11-12, between 10 p.m. and 2 a.m. on roads within a one-mile radius from intersection of Peck's Road and Wahconah Street; Garland Avenue and North Street; Warwick Street and Pomeroy Avenue. The rain date will be Wednesday, Sept 12. A map of the area in question can be found here.
 
Residents may opt by submitting an exclusion form that can be found here
 

 


Tags: mosquito,   mosquito spraying,   

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