Regional Gardening Reports :: National Gardening Association

In the Garden:
Lower South
September, 2007
Regional Report

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This ladybug larva will make fast work of these aphids.

Beneficial Insects to the Rescue

I understand, sometimes it feels like it's just you and your garden against them. I mean the pesky beetles, aphids, mites, caterpillars, and other creepy crawlers that just don't seem to understand that your garden is intended for your aesthetic and culinary pleasure.

It may seem like the only thing that stands between the marauding hordes and our plants is us, with sprayers in hand. In fact, the vast majority of pest control is handled by Mother Nature, who keeps things in a reasonable balance most of the time. We really just deal with the tip of the iceberg.

Out in the landscape and largely unseen by us, a war is going on. Thousands, no make that millions, of pests are preparing for the attack. Aphids born pregnant are reproductively active and having "babies" within a few weeks with the potential for geometric population growth that would leave them knee deep in the landscape by the end of the season! Moths are laying eggs by the hundreds, which could hatch out into an army of caterpillars large enough to devour every leaf on our plants. But the anticipated annihilation never comes. The reason is because at the same time our allies are at work.

Our Allies
Big-eyed bugs and minute pirate bugs roam the foliage looking for eggs. When they find one, they place their long slender mouthparts inside and suck out the contents ... another caterpillar that will never hatch.

Assassin bugs, ambush bugs, spined stilt bugs, and wheel bugs are out hunting for caterpillars and other pests. Praying mantids, web-building spiders, free-roaming spiders, and beneficial mites make the garden an even more treacherous place for pests to live.

Tiny parasitic wasps barely larger than a gnat, such as the encarsia wasp and the trichogramma wasp, fly about in search of eggs in which to lay their own eggs. The wasp larvae hatch out and consume the insides of the pests, turning them into hollow shells before emerging to continue the cycle.

Caterpillars that do survive are at great risk of being eaten by birds or snatched up by paper wasps patrolling the garden in search of food for their young. Entomologists have estimated that a paper wasp nest can consume 2,000 caterpillars in a season! Potter wasps capture caterpillars and immobilize them and stuff them into their mud nests as food for their young that will soon hatch inside.

Ladybugs and their voracious larvae, which devour aphids, are out and about. Ground beetles patrol the soil surface in search of insect eggs, caterpillars, and other favorite snacks. Lacewings swoop down to lay eggs on silken strands. Their larvae, like tiny alligators with ice-hook mouthparts, are hungry for a meal of aphids, mealybugs, and other insects.

So you see, the vast majority of pest control IS done for us! Occasionally something swings out of balance here and there, perhaps due to the weather or our throwing the balance off with an injudicious use of a broad-spectrum pesticide. When this happens we may need to step in with a carefully selected and targeted low-toxicity spray, but such is the exception not the rule.

We can learn to attract and protect our allies in the garden. The more they do, the less we have to do. Or put another way, "When you kill a beneficial insect, you inherit its job." Stay tuned for next time when I'll talk about how to attract beneficial insects to our gardens and make them want to stay.

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