Bothered by these little suction cups? Please do not spray. | Opinion
By Claire Whitcomb
I read the statistics. I know that bumblebee populations have declined by 90% and that up to a third of firefly species are at risk of extinction.
That’s why I grow milkweed and pollinating plants and leave dead leaves for the firefly larvae. But am I making a difference? Am I seeing more monarchs? Mason bees? Moths?
The only insect I can vouch for is the mosquito. Populations appear to be thriving, judging by street signs, flyers, and billboards promoting mosquito spray services.
On my side of the fence, the problem is this: if someone sprays a fine mist of pesticides on the shady, flowerless areas where the mosquitoes are resting, it won’t just kill the mosquitoes.
“It can impact bees, butterflies, moths, caterpillars and insects that birds depend on for food,” says David Mizejewski, a naturalist with the National Wildlife Federation.
Risks to pollinators can be masked by the fact that household sprays typically contain synthetic pyrethroids and insecticides related to the natural pyrethrins found in chrysanthemum flowers. Although chemically similar, synthetic pyrethroids are not eco-friendly or plant-based. They are broad-spectrum nerve toxins that the EPA says are “extremely toxic to bees and other insects.”
In a domestic environment, synthetic pyrethroid sprays kill not only during the application process, which is brief. They dry on the foliage and persist, turning the simple act of landing on a leaf into a life-threatening event.
“Permethrins and other pyrethroids can be toxic to insects that eat or touch them during the period of residual activity, which is typically two to four weeks after application,” says Dr. Paula M. Shrewsbury, Associate Professor of entomology at the University of Maryland.
What insects are we talking about?
Bees to start.
Unlike honeybees, a European import, native bees, which include bumblebees, leaf cutters and mason bees, make their nests in the ground or lay eggs in stems, old logs and aboveground cavities.
With the exception of bumblebees, most native bees do not live in hives. Males are banished from the nest once raised. Heather Holm, author of four books on bees and pollinators, explains that “until they die, solitary male bees are in the landscape, clinging to foliage, sitting in flowers. They would be directly impacted by spraying the foliage.
“Step outside on a cold morning,” says Colin Purrington, nature photographer and avid entomologist in Swarthmore, Pennsylvania, “and you might find a few dozen male bees crowded on a single plant with their mandibles. Several species might be there, just hang out.
Later in the day, you may see fireflies and moths resting in the shade, dodging predators and conserving energy for nighttime flights. On the underside of leaves – a prime spot for mosquito sprays – you might find butterfly eggs. Butterfly and moth caterpillars might nibble their way to maturity – or get sucked in by a hungry bird.
What about disease control?
Area-wide disease control and suppression of mosquito populations is the responsibility of county mosquito control agencies. “We encourage people not to spray their own backyards and let the county deal with it,” says David Brown, technical adviser for the American Mosquito Control Association. One reason, he says, is the growing resistance of mosquitoes to pyrethroids. “If you can manage the habitat in a way that reduces the likelihood of mosquitoes emerging, that’s a win-win.”
Start by removing standing water. Female mosquitoes will lay eggs in the half inch of water lingering in a flowerpot saucer. Common breeding grounds include old tires, corrugated pipes, leaf-clogged gutters, tarps filled with puddles, and forgotten children’s toys.
Vigilance will not prevent mosquitoes from flying in from your neighbors’ yards. Effective ways to ward them off include oscillating fans (mosquitoes fly weakly) and traps that attract female mosquitoes and prevent their eggs from hatching. Purrington uses a selection in his garden and discusses it on his website. Douglas Tallamy, author of the best-selling “Nature’s Best Hope,” popularized a homemade trap with a five-gallon bucket, water, straw, and a Mosquito Dunk, a larvicide.
Targeted strategies are cheap, effective and much better for pollinators.
Claire Whitcomb is a sustainability writer and president of the Madison Environmental Commission.
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