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While most New Bedford residents sleep, John Moniz is out in his truck. Between 2 and 10 a.m., the Bristol County Mosquito Control Project general foreman cruises around the county’s parks, yards, and neighborhoods spraying low-dose Duet, an insecticide, into the early morning fog.
His work is part of statewide efforts to curb the pesky mosquito, which, apart from being annoying, can spread deadly diseases such as West Nile virus and Eastern equine encephalitis (EEE). Since 1959, the Bristol County Mosquito Control Project has trapped, tested, and sprayed mosquitoes in coordination with the Massachusetts Department of Public Health, most often carrying out its efforts in the wee hours of the morning.
That’s because most mosquito species are what project superintendent Priscilla Matton calls “nightbiters,” meaning they’re most active at dawn and dusk, when most other insect species are asleep. As soon as the Duet touches a mosquito, it’s dead.
Matton assured that the insecticide is nontoxic to humans and other mammals. Still, the sprayers try to avoid any people who might be in the park after dark.
The streets are barren at 4 a.m. when Moniz’s truck passes around Hazelwood Park in New Bedford’s South End. A thin cloud of mist unfurls from the truckbed; the sea wind off Clark’s Cove carries it up the hill and over the park.
Matton watches the truck go by. After the spraying is done, she doesn’t have the luxury of going back to sleep.
“I’m going back to work,” she said.
The right to bare arms
Not all bloodsuckers are created equal.
There are 52 different species of mosquitoes in Massachusetts, but MassDPH only monitors for 13 species known to carry harmful diseases.
While weekly sprayings help curb “nightbiter” mosquitoes, the region has steadily seen an increase in “daybiters,” which, as the name suggests, bite during the day. Daybiter species like the Asian tiger mosquito, first spotted on the South Coast in 2009, are known to carry both West Nile Virus and EEE, prompting both the county and MassDPH to monitor their numbers.
But just how many mosquitoes are there in Bristol County?
Matton laughed. “There’s no way to know,” she said.
The Bristol County Mosquito Control Project monitors mosquitoes much like you would any animal: by baiting and trapping a select few. But the bait in this instance is unusual. Rather than leave out a cup of tasty blood, Matton’s team attracts mosquitoes to the trap with a stinky solution designed to mimic the fetid standing water where they lay their eggs.
“They don’t care about water quality,” Matton said. “The stinkier the water, the more bacteria for their larvae to eat when they hatch.”
Once she’s trapped them, Matton sends the sample mosquitoes to MassDPH to test them for diseases. So far, the state has detected 35 instances of West Nile Virus in mosquitoes this summer, none in Bristol County. There have been no positive samples of EEE in mosquitoes yet this summer, although Matton said cases tend to pick up later in the season.
Thanks in part to the recent drought, Bristol County has observed the lowest mosquito count in nearly a decade, Matton said.
That’s good news for those who value the right to bare arms. But the season is still young, Matton warned, and so are the mosquitoes. Just one major rain event could spur a breeding frenzy.
“Mosquitoes can act very quickly,” Matton said. “It’s just a matter of how long that water sits before it gets absorbed into the ground.”
Get protected
Anyone in Bristol County can request to have their yard sprayed free of charge. Residents can also opt out of pesticide spraying if they choose.
To stay safe outdoors, Matton recommends that residents use bug spray that contains DEET or other EPA-recommended insecticides; wear light, long-sleeved shirts and long pants; and empty any sources of stagnant water on their properties.
When Moniz and his team are done with their spraying for the night, they return to treat catch basins and other sources of standing water with BTI, a larvicide derived from a naturally-occurring bacteria found in soil.
“Mosquitoes are filter feeders, so they eat it and it actually ends up exploding their stomach,” Matton said.
Despite the grisly image, Matton again assured that the larvicide does not harm other types of insects, since few species hang out in standing water the way mosquitoes do. The same substance is also used to control black flies in flowing rivers in other states.
But why do some people seem to get bitten more than others? Matton said there’s a range of possible factors, from blood type to the amount of CO2 a person emits to the chemical makeup of their sweat.
For some chronic victims, it might be worth taking a shower before going outside.
“Some are attracted to stinky-feet smell,” Matton said.
Email Brooke Kushwaha at bkushwaha@newbedfordlight.org.
