Why Natural Insect Control Works Better

Interplanting flowers with food crops will promote a balanced insect ecology, which in turn will enable natural insect control without the use of toxic pesticides.

| June/July 2010

I’ve always been an organic gardener. Early on, I thought natural insect control meant using an “organically approved” insecticide, such as rotenone, to defeat leaf-eating insects — especially my arch-nemesis, the Colorado potato beetle. I dusted my potato patch several times a season in a struggle to keep the beetle’s exploding population in check, barely managing to bring in the crop. But as I learned more about the ecology of insects such as ladybeetles, lacewings, praying mantises, and assassin bugs — what some call “the good guys” — I worried that blasting away with a powder intended to kill might not be doing them any good either.

One spring I vowed to use no rotenone at all in my potato patch, even if it meant losing the crop. I was amazed to find only five potato beetles on my potato plants during the entire season. I took that as luck-of- the-draw seasonal fluctuation — until I bumped into my neighbor across the road, whose garden was less than 70 yards from my own. “My, my,” she wailed, “ain’t these potato bugs just awful. I dust, and I dust, and I dust — and I’m still out here every day, picking ’em off by hand!”

That was my epiphany about the true nature of the teeming insect community around me, and my garden’s relationship to it. From that moment, I have never used a granule of toxin — however reputedly benign — to deal with insect challenges in my garden and orchard. I now find the potato beetle to be one of the easiest insect competitors to deal with.

How to Sustain a Natural Ecosystem

Using natural insect control makes perfect sense to me now. Who wants to eat food that’s been sprayed with toxic chemicals better suited to chemical warfare than gardening? According to the Environmental Protection Agency, American agriculture uses toxic pesticides at a rate of more than a billion pounds annually, and only a small percentage of those chemicals actually make contact with a target insect. The remainder is irrelevant to insect control, but constitutes an assault on the rest of our ecosystem. Pesticides suppress the soil food web (the foundation of soil fertility), pollute groundwater and natural water systems, and destroy vital pollinators and other species.

My fundamental mistake was assuming “organically approved” insecticides made more sense than using any other garden chemicals. While their “non-target” impacts are not quite so drastic they still do more harm than good. Most are broad spectrum in their effect, and can thus wipe out non-target species. To me, the fact that my greatest success with potato beetles came when I ceased doing anything at all to defeat them calls into question the whole strategy of preventing crop damage by killing whole classes of insects. My decision to reject that model — along with the fact that I’m a lazy old gardener who has always had plenty of “the wild” coming in his garden — made possible a natural, spontaneous, unplanned solution to my problem: Flowering weeds provided food and shelter for insects (no longer suppressed by the rotenone) that eat the eggs and larval stage of the potato beetle. The rest, as they say, is history.

Encourage Insects in the Garden

Plants, being immobile, make a deal with their insect buddies: food and shelter in exchange for moving pollen to other plants of their species, initiating production of seeds. Thus, the more flowering plants, the more insects in the ecology — and the more insect species, the more likely any overly successful species is going to be targeted as lunch by predator species. This simple law of population dynamics suggests establishing a balanced insect ecology as the key to preventing crop damage in the garden and orchard. Far from engaging in a “war on insects,” it’s wise to try to maximize the numbers of insect species, ensuring the abundant presence of species that feed on those insects with a taste for our crops.

6/23/2018 6:05:35 PM

How do you get rid of box elder bugs?

Matt Loggins
12/24/2013 9:12:41 PM

Black widows hate tomato plants and marigolds. I find pruning branches from my tomatoes helps increase air flow, which decreases gnat activity. Black widows liked to make their home under the edges of the vinyl siding around my house... slipping the tomato branches under the edge of the vinyl has completely stopped black widows from making homes anywhere I place them. They have a strong smell, I think that's what it is. They're also nightshades, might have something to do with that.

7/6/2010 11:45:23 AM

Squishing Black Widows worked for me. Try using a thin flat stick, ex. a ruler,to get down into the holes in the blocks. And don't worry - they won't attack or jump at you, but they may try to climb farther in, so be quick in your attack. I had a horrible lot of them in my yard the first summer, but since my killing spree, they have been significantly better - only a handful since then. And make sure to check under the lip/rim of your potted plants before you pick them up - they like it under there, too. Good luck!

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