Ecology Blog

Itís A Bugís Life
Myth: Pesticides only kill bad bugs

Myth Explored
Whether itís stem borers in the roses, caterpillars in the tomatoes or an inconvenient waspís nest located directly over your back door, insects can take a lot of the joy out of your little corner of the Great Outdoors. They can stunt your plants or kill them outright. They can devour your fruits and vegetables. The wasps may sting careless kids and curious dogs. The mosquitoes will bite everybody, curious or not.

Itís only natural that home gardeners would turn to pesticides to gain a little relief.

Unfortunately, pesticides come with problems of their own. Some are so dangerous that it requires a special license to use them at all. Most are more dangerous than you might suspect. A wise gardener pays close attention to the details, reads the labels and follows the directions to the letter. Playing with pesticides is a dangerous game. Letís learn a few of the rulesÖ.

The Situation
Follow I-90 east out of Seattle and you'll be startled by the abrupt transition between the coastal forests and the high desert. The Cascade Mountains trap much of the rain and leave vast swathes of the interior too dry for agriculture. By the time you pull into Yakima, with its irrigated apple orchards, it feels like you've discovered an oasis.

But be prepared to roll up your windows when the crop dusters come by. Even here, in this island in the desert, the bugs have found their way to the food supply. No matter where you are, and no matter what youíre trying to grow, it will be only a matter of time before the pests show up.

Sometimes the damage they do is tolerable. But sometimes the infestation is so bad that pesticides seem to be your only option. Letís talk about that.

The Problem
Humans have been battling bugs for a very long time, and weíve come up thousands of solutions. But in general, pesticides fit into three broad categories. Some pesticides are designed to be ďsystemic,Ē meaning that the plants draw the appropriate chemicals up through their roots and render the entire plant toxic to attacking insects. Others kill through direct contact with the insectís body. Bacteriological pesticides like BT (Bacillus thuringiensis) work by introducing bacteria that secrete toxins after theyíve been ingested by the insects.

Even ďorganicĒ farmers deploy pesticides. They wonít use artificial chemicals or systemics, but if an infestation gets bad enough theyíll spray BT or natural contact-killers like the chrysanthemum-based pyrethrum, which breaks down quickly in the environment and wonít be absorbed by the plant through its root system. Note that while pyrethrum is light years better than DDT, itís still a nerve toxin, and very dangerous to humans and animals when itís being applied. Bottom line, pesticides are poisons.

Even if the current research indicates that a particular pesticide seems to be harmless to humans, who really wants to be the guinea pig?

Furthermore, not all of the bugs in your garden are your enemies. Insects like ladybugs, lacewings, and praying mantids are actually your allies. They make their living gobbling up your garden pests. Others, like bees and butterflies, are pollinators. Many of your plants canít get along without them. And some bugs are just fun to have around, like the lightning bugs that entertain the kids on a summer evening. (Lightning bug larvae are also useful predators.)

Pesticides will kill good bugs right along with the bad. The same systemic pesticide that defends your flowers from aphids will also poison the bees and the other pollinators when they eat the pollen and the nectar. A knock-down spray that gets rid of grubs and caterpillars will also kill your ladybugs and lacewings.

And by killing good bugs along with the bad, pesticides throw your whole backyard ecosystem out of whack. As the poison degrades and the insects return, it will be the pests who arrive first, looking for their food supply. The predators will follow, but probably not before the pests have already had their fun. So, having used the pesticide once, you may find that youíll have to do it again and again.

The Solution
Consider pesticides; any pesticide, to be a weapon of the last resort. Itís natural to have a few bugs nibbling on your plants, and thereís no need to panic as long as their natural predators seem to be keeping things from getting out of hand. The discovery of one caterpillar in a row of healthy tomato plants is probably not a portent of doom. Itís not yet time to reach for the heavy artillery.

Design your garden to be attractive to natural predators. Many predators supplement their diets with pollen and nectar, so they like a garden that blooms all summer. Planting a variety of flowers alongside those home-grown tomatoes doesnít just make your garden prettier; it helps defend it from insect attack.

When you do think you have a serious infestation, donít act until youíve done your homework. Examine your plant closely, figure out what the pest is, and research the available solutions. You may find that you can control your particular problem with relatively non-toxic measures, like insecticidal soaps or vegetable-based horticultural oils. (Some plants can be damaged by the soaps and oils, but many wonít mind them a bit. Read the label.)

Even if you do decide that a pesticide is the only option, be aware that pesticides are not all alike. They all pose different levels of risk to you and to your backyard environment. They will be labeled accordingly. ďCaution,Ē means the product is considered to be reasonably safe, so far as anybody knows. ďWarningĒ means the stuff has known toxicity issues. ďDangerĒ means that youíll definitely get yourself, your children or your pets into serious trouble if you make a mistake. If a product with low toxicity will solve your problem, why take chances with anything uglier?

No matter what pesticide you use, follow the directions to the letter.

What You Can Do
Read the label every time you handle a pesticide. Read the whole thing.

Buy only the amount of pesticide you need for the project at hand. Why keep poisons in storage?

Leave pesticides in their original containers until you use them, and keep them locked away where pets and children canít get at them.

Know the signs of pesticide poisoning, and learn the first aid instructions Ė backwards and forwards -- before using the product.

If youíve got old pesticides stashed away they may not even be legal anymore. Read the label, and if necessary, dispose of them properly.

Wear protective clothing when using pesticides. Donít smoke, donít eat, donít drink Ė donít get the stuff into your mouth.

Donít use a pesticide on a windy day, when you canít control where itís going.

Pay strict attention to what the label says about the amount of time needed before a treated area is considered to be safe for humans, pets or wildlife.

United States EPA: About Pesticides

University of Illinois: Alternative Methods for Insect Management

Cornell University: Biological Controls for Insect Pests

Colorado State University Extension Service: Pest Control with Insecticidal Soaps

Colorado State University Extension Service: Pest Control with Horticultural Oils

Environmental Working Group: Which Produce Has the Most/Least Pesticide Content?

University of Illinois: Attracting Beneficial Insects to Your Garden

Colorado State University: Attracting Beneficial Insects to Your Garden



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