Are Fly Sprays Safe?

It’s summer in New Zealand, and although I’ve never had a mosquito problem around my home (camping is another story!), the flies can be annoying. Most of the time, this isn’t a big issue, but when I start cooking—or have the crock pot on all day with a stew or pot roast inside—they always show up.

If you’ve read other articles on this site, you’ll probably guess that I don’t much care for industrial poisons, so the fact I don’t use fly spray in my home won’t surprise anyone. In fact, it concerns me that on tv we’re seeing ads now for automatic fly sprays that send spurts of insecticide into your household air at regular intervals or whenever they detect motion. As if the insects are a greater threat to your health than the toxic chemicals released by these products.

Some years ago, I bought a little sticky flower-shaped bug-killing decal and I put it on the window in the kitchen. It looked and smelled benign enough, and I was curious if it would kill or repel flies. Big flies weren’t bothered by it much, but all summer long, the dead bodies of little flies and other insects gathered in a neat pile below the sticker on the windowsill for me to remove daily. At the end of the summer, I removed the decal and threw it away. For the next three summers—until I moved to another house and so I don’t know what happened after that—little piles of small flies and bugs would continue to accumulate on that corner of the windowsill. Clearly, the residual insecticide from that sticky decal was still killing bugs years after it had been discarded (and the window, of course, cleaned numerous times). Food for thought, isn’t it?

 According to the US Environmental Protection Agency, three quarters of us use commercial pesticides inside our homes, and some 80% of the average person’s exposure to pesticides comes from inside the house[i]. Insecticides, however, are not species-specific. Although insects may be affected more quickly and completely than us humans or our pets—and do note that in the fine print on insecticide cans it says not to use the products in rooms with fish tanks—we are still affected by these toxic chemicals. Common side effects include irritation to eyes, nose, and throat, damage to the central nervous system, kidney damage, and an increased risk of cancer. Some pesticides can also cause headaches, dizziness, muscle twitching, and nausea[ii].

But what about the “natural” plant-based insecticides. Surely they’re safe. Yes? Well, no. Although the folks who make them try hard to convince us they are.

Plant-based insecticides are usually based around Pyrethrin, which comes from feverfew, or Pyrethrum, from chrysanthemums. Permathrin is a synthetic copy of these plant poisons. Like more traditional insecticides, these plant-based compounds can cause (for us humans) sneezing, coughing, wheezing and a runny nose in the short term, and can disrupt the endocrine system in the long term because they mimic estrogen.[iii] They are not recommended in homes where people have asthma or allergies.[iv] They are also carcinogenic, affect the liver and thyroid gland, and basically act as excitatory nerve toxins.[v]

What’s the alternative? Well, a good, old-fashioned fly swatter might not seem very trendy or hygienic, but it does the trick and it won’t affect your liver. I had a Labrador once who loved catching flies. And I’ve known a couple of teenage boys who took great delight in demonstrating their dexterity by catching flies with their bare hands.  If these options aren’t appealing or available to you, you can mix a few drops each of lavender oil and lemongrass essential oil on a soft cloth and wipe your windowsills with it—it smells nice and flies don’t like it. Eucalyptus oil and mint are also natural fly repellents.[vi]

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[i] http://www.epa.gov/iaq/pesticid.html

[ii] Ibid.

[iii] http://www.toxicsinfo.org/pests/Pyrethroids.htm

[iv] http://www.raidautomatic.com.au/faq.html and  http://www.beyondpesticides.org/infoservices/pesticidesandyou/Summer%2005/asthma%20article.pdf

[v] http://www.toxicsinfo.org/pests/Pyrethroids.htm

[vi] http://eartheasy.com/live_natpest_control.htm offers a variety of suggestions for the natural control of a variety of insect pests from flies to ants to cockroaches.