Mosquito Spray Endangers Vegetable Gardens, Pollinators, and Birds
May 19, 2017
Linda Watson in bifenthrin, health, local, make a difference, mosquito spraying

A new problem has hit for families trying to grow vegetables at home: mosquito spray. More and more of my neighbors are having their yards sprayed for mosquitoes. The spray drifts into other yards when there is any breeze. The technicians usually face the neighboring property as they blast plants at the borders, spraying 20 feet or more onto property that was not supposed to be sprayed. Vegetable gardens, laundry, pets, fish in ponds, solar cookers, and even children can all come into contact with the spray. Ironically, even mosquito predators are killed by the spray, which makes the problem worse.

Using a spray gun to spray for mosquitoes, Brisbane, 1946. Public domain via Wikimedia Commons

Read on for what this means for birds and what the toxic ingredient in many sprays does. Mosquito spraying is a big local issue that calls for personal action, new regulations, and more research as we try to create sustainable communities. Find out about a less-harmful alternative and other steps you can take below.

Mosquito Spray, Insect Decline, and Birds

Science Magazine asks this week Where Have All the Insects Gone? Scientists don't have all the answers yet, but suspect neonicotinoid pesticides used on non-organic crops and loss of habitat. A yard sprayed with mosquito spray is a lost habitat for mosquitoes, butterflies, bees, and more. A friend in Virginia told me she had noticed that there were no insects in her community vegetable garden this year, a big change. She said that a man who runs a local birdhouse project reported finding birdhouses full of birds who had starved to death. No insects, no insectivores.

An Illusion of Safety

I was surprised when a neighbor said that Mosquito Authority told her its spray only killed mosquitoes. At the time (summer 2016) Mosquito Authority website said:

Our technicians go through extensive training in the proper application process with an emphasis on avoiding application to beneficial insects like honey bees.... So as much as we love honey bees, we love our children more. And as much as we want to protect beneficial insects, we can’t do so at the expense of performing the best mosquito control possible.

That language is now gone, replaced by:

As a result, many of these same people are implying (and in some cases flat out accusing) pest control companies like us of killing off the honey bees. We’ve researched it. We could list all the facts, figures and research we’ve found. But the truth is, we are perfectly willing to leave that argument to those who feel compelled to argue.

Warning: you might feel as "compelled to argue" as I do after reading the studies below.

I called the local Mosquito Authority to check on the active ingredients in their spray. The person I spoke with said the active ingredient is Bifenthrin 7.9. That's a synthetic pyrethroid that kills many insects by altering nerve function and causing paralysis. He assured me that it was not harmful to children or pets. 

The EPA does have some comforting language about pyrethroids for humans, which made me realize why people feel safe using it. But even the EPA says:
The EPA has determined that developmental toxicity studies (DNTs) previously required for pyrethroid insecticides do not adequately characterize potential susceptibility of the young.

Scientific Studies Show Danger of Mosquito Spray

Bifenthrin Toxic to Fish and Bees, May Cause Cancer in Humans

Here's an article from Duke, The Chemicals that Promise Summer without Mosquitoes, with a section on bifenthrin, which says bifentrin is "highly toxic to fish and small aquatic organisms, very highly toxic to bees, and classified by the U.S. EPA as a possible human carcinogen based on research on mice" but not on rats. Side effects in humans may include DNA damage, endocrine disruption, fertility issues, and more. You can see why you might be concerned about spraying in your neighborhood:
People and pets are advised to avoid areas recently sprayed for a minimum of 20 to 30 minutes until the solution dries to avoid acute effects, which according to the National Pesticide Information Center can include numbness and itching with contact. Breathing in bifenthrin can be an irritant and eating it is a no-no. So if you have a toddler running around your backyard, pulling grass and leaves, and putting them in his or her mouth, it’s probable that they are ingesting some pesticide. Spray drift can be an issue and water body contamination is to be avoided. Pets can experience acute effects as well, including vomiting, reduced activity, and partial paralysis.

Bifenthrin is Highly Toxic to Bees, But "Sublethal" Doses Bad Too

The Purdue Extension Service lists bifenthrin as highly toxic to bees and says beekeepers within 2 to 3 miles should be notified the night before spraying. (Two or  three miles!) This beekeeper's website has a good post about a study on the sublethal effects of bifenthrin on bees, which says:
Lately more attention has been given to sublethal doses because, although they might not kill an adult bee outright, they can have serious consequences to the survival of young bees and to the future of the whole colony. Imagine a human who is poisoned enough to have brain damage but not enough to die. That would be a “sublethal” effect.... The researchers found that in honey bee colonies exposed to sublethal amounts of these pyrethroids, the queens didn’t lay as many eggs, the number of eggs that hatched was far fewer, and the number of hatchlings that made it to adulthood was even fewer. Since the honey bee life cycle—from egg to adult worker—is just 21 days, you could go from a very strong hive to a very weak one in less than a month.

More Peer-Reviewed Journal Articles on Bifenthrin

In case you don't yet feel "compelled to argue," here are a few more scientific articles about the active ingredient in mosquito spray.

What Can You Do To Avoid Mosquitoes and Not Poison the Planet?

Red-winged blackbird ready to eat your mosquitoes by George Francis Burba. Public domain via Wikimedia Commons

Some of my neighbors have switched to an organic garlic spray that kills mosquitoes on contact but then just repels them for several weeks. The bugs evidently have a keen sense of smell. My neighbors say their yards smell a little like pizza for an hour, then they don't notice it. Mike at Gardens Alive discusses garlic spray for mosquitoes and two non-toxic personal sprays. Toxic Free NC recommends using lotions or creams instead of sprays to avoid breathing in harmful substances.

Better yet, invite birds to eat your insects. Even birds who eat seed feed insects to their babies. Remove the standing water that they need to breed, too. Check your gutters and remove any water traps like old tires or saucers under potted plants. Change the water in birdbaths every week.

We should urge mosquito companies to act as good citizens, but my interaction with them over the past few years leads me to think that won't be enough. We should urge legislators to adopt new laws that require:

  • Notifying neighbors of the spraying schedule so they can keep their pets inside, not hang out laundry that day, and take other precautions.
  • Spraying in a way that minimizes drift, such as spraying along the property line instead of across it. Spraying should not be done when it's breezy out.
  • Protecting the technicians, who are exposed to high levels of spray as they work.

What's your experience been with mosquitoes and mosquito-spraying companies? Please log in and share your comments below. May you have a bite-free summer!

Photo credits: Using a spray gun to spray for mosquitoes, Brisbane, 1946 and Our Bird Friends by George Francis Burba. Public domain via Wikimedia Commons.

Article originally appeared on Cook for Good, home of Wildly Affordable Organic and Fifty Weeks of Green (http://cookforgood.com/).
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