The Iowa Gardener: Why I’m giving up on insecticides

Cardinals and house finches, gathered at a backyard bird feeder in Marion in this file photo. Killing grubs with insecticide can be hurting the birds and pollinators that gardeners try to nurture. (James Durbin)

I'm not an organic gardener, but as a former farm kid, I have a deep, abiding respect for Mother Nature. And for that reason, after 40 years of gardening, I'm resolving to swear off insecticides.

That includes even the organic ones. Here's why: Insecticides, whether they are organic or not, kill insects. Lots and lots of insects. All pesticides are fairly indiscriminate — they kill beneficial insects, including bees, right along with problem insects. Further, insecticides can also hurt other animals in the food chain, like birds.

Very few insecticides, if any, are so selective that they kill only one problem insect. For example, if I apply an organic insecticidal soap spray to my greenhouse tomatoes because they have spider mites, I might also end up killing any Phytoseiulus persimilis, a beneficial mite that feeds upon, ironically, spider mites.

Other popular insecticides like, Imidan, malathion and Sevin have been demonstrated in study after study to be harmful to a wide variety of insects, including our beloved honeybees and other essential pollinators.

Insecticides impact more than simply insects. Case in point: For years, grubs keep damaging part of my back lawn. So I’ve had my lawn service apply a special grub killer, which doesn't even seem to be working well. It also may be killing beneficial beetles and fireflies. But the impact gets even broader. Sparrows, robins, other birds, and other wildlife like to eat those grubs. In fact, I recently came across a statistic that our North American bird population has been reduced by 30 percent since 1970 when I was a kid. My attempts to kill grubs, I realized, are probably also hurting the birds that I try so hard to nurture with a bird bath, bird feeders, and with plantings of purple coneflowers and sunflowers.

There are other many other ways to control destructive insects that don't kill beneficial insects. Gardeners have used them for decades before the advent of mass-produced insecticides:

Avoid plants that are highly susceptible to insect damage in the first place. When in doubt, choose Iowa natives. They’ve been around for centuries, have evolved to fend off local insect attacks and are generally all-around tough.
Follow good garden practices. Make sure sun-loving plants have plenty of sun (when they are weak and spindly, they become predatory insect magnets). Keep all plants weeded so that they aren't weakened by competing plants. Mulch to conserve moisture and prevent soil-borne diseases from splashing on their stems and leaves. Work in plenty of compost into the soil each year to feed plants to keep them strong and to attract beneficial earthworms.

If nothing else, swearing off insecticides lets me be cheap and lazy. I don't have to spend any money on them. I don’t have to take time to research, purchase and repeatedly apply them. I also don't have to worry about how to dispose of any leftovers in a responsible way. Helping nature can be win, win, win.

I’m convinced I can have a beautiful, well-tended garden without insecticides. Besides, my yard and garden are not my livelihood. There is not one plant in there that is critical. The worst thing that can happen is that a neighbor might raise an eyebrow at the patch of lawn that's damaged by grubs or the zucchini plant that got attacked — again — by squash bugs.

The bottom line is that I garden because I enjoy nature, not because I want to poison it.

Veronica Lorson Fowler is co-publisher of the Iowa Gardener website at www.theiowagardener.com.