Entomology professor Stephen Rich weighs in on the safety of pesticides being used in new home sprinkler systems.
| Thomas Caywood
The Smiths paid $2,500 last year for the system, which works on a timer and sprays a mist of mild pesticide in the mornings and evenings, when mosquitoes are most active.
``We love it. We're in our yard all the time now," Fran Smith said. ``Once in a while you might see a mosquito, but I haven't been bit since we got it."
Their boys, ages 13 and 9, now swim in the backyard pool and play on the sand volleyball court without needing bug spray. Ed Smith even sets up his movie projector and a screen, to show films to his children in the yard.
``The kids get their little sleeping bags to lay on, and we watch movies," Fran Smith said.
The idea of spraying twice a day to eliminate mosquitoes and then lolling in the backyard might seem extreme to some, when pesticides have been linked to illnesses among humans and damage to the environment.
But specialists say the pyrethroid pesticide used by the Smiths is relatively safe.
Pyrethrum is produced naturally in chrysanthemum plants, and man-made versions synthesized in laboratories have been used as insecticides for more than a century, said Stephen Rich, an entomologist at the University of Massachusetts at Amherst and a specialist on pesticides.
``Pyrethroids are very toxic to insects. They attack the central nervous system," Rich said. ``But the really neat thing about them is they don't have much toxicity to mammals at all. They've been used for a long time to spray grain products for livestock and so on."
The compounds break down rapidly under sunlight and thus do not accumulate in the environment like harmful pesticides such as DDT, Rich said, adding: ``It's one of the safer insecticides there is."
Pyrethroids also are used in many bug sprays, and in flea treatments for dogs and cats. There's even a line of insect-repelling clothing called Buzz Off, which comes with the compound embedded in the fabric.
Fran Smith said she much prefers to have pyrethroids sprayed along the perimeter of her lawn twice a day to frequently slathering her sons with bug sprays containing substances such as DEET and other potentially noxious chemicals.
Worse, there is always the chance that the boys might be bitten by a mosquito infected with a potentially deadly virus.
Mosquitoes infected with eastern equine encephalitis were detected this month in Carver. Mosquitoes trapped in Needham last month tested positive for the West Nile virus, health officials said.
Last summer, mosquitoes that had been trapped in Holliston and Westborough were found to have been infected with eastern equine encephalitis, while a mosquito from Westborough tested positive for the West Nile virus.
``I know it's an aggressive way to get rid of mosquitoes, but, in my eyes, it's become necessary," said Anthony Santoro, whose Waltham-based company, Mistguard Mosquito Control Systems LLC, installed the spraying system at the Smith home.
Similar systems have been popular in marshy parts of Texas and across the South for years, but are catching on here only now.
The misting system's quarter-inch tubing and metal spray nozzles can be buried in the yard like in-ground sprinklers, or installed above ground, along a fence, for example. A tank-and-pump mechanism about the size of a small trash barrel is installed in an inconspicuous spot along the fence, or in a garage. Newer models are even smaller, Santoro said.
The chemical spray can harm some plants and flowers, but does not hurt anything that can survive a New England winter, Santoro said. ``We arrange the system to be a little further away from those delicate plants," he said.
Lucia Dolan, a member of the Committee for Alternatives to Pesticides, an offshoot of the Green Decade Coalition in Newton, said the pyrethroid pesticide may not pose much of a risk to humans, but it could be harmful to the environment.
``According to what I've seen, it's indiscriminate," Dolan said. ``It's toxic to bees and toxic to certain kinds of fish. If it's used near water, it could be hurting fish."
The spray starts to cut down on mosquitoes after three days, but the most dramatic results come after two weeks, a full mosquito breeding cycle, according to Santoro. A one-gallon container of the insecticide costs $130, and can last for several months, depending on the size of the yard.
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