David Robson: Turn Mother Nature against her own pests

David Robson

It’s hard to garden without the threat of insects, diseases and weeds.

Pests compete for water, nutrients, light and space, and they can take a healthy plant and turn it into a pile of mush. Few would say there is nothing worse than finding half a worm in an apple.

Life would be so simple if pests didn’t exist. Personally, those problems keep us humble and allow nature to keep the upper hand. But we have pests, and our job is to minimize their impact.

You cannot control 100 percent of pests. That’s a pipe dream. The idea is to manage pests to reduce their impact.

Sharing the garden

The best way to handle pests is to let nature manage her delinquents. And one of the best ways is to encourage birds and other insects into the garden to feed on unwelcome bugs. Birds don’t do much for controlling diseases and weeds.

Birdhouses and feeding the birds during the winter is one way to advertise you have something worth sticking around for. The more birds and the bigger variety of winged creatures you have, the fewer insect problems you’ll notice.

Not all birds are created equal. Few would advocate sparrows and pigeons, though some species of both aren’t too bad. It’s the colorful songbirds, such as cardinals, finches and robins, that we want.

There are always downsides. Cardinals are adept at eating caterpillars, though maybe not the ones you want eaten. Cardinals, especially young ones, will easily land and perch somewhat unsteadily on your dill and fennel plants and nibble at swallowtail larva you were attracting with the members of the carrot family.

Inviting feathery friends

Birds also need water. A fountain or just a nice dish of water you change daily should suffice.

Birds need places to rest, too. Trees and shrubs are ideal as they are off the ground and away from cats and other unfriendly creatures. People with more trees and shrubs will have more birds, especially the good kinds.

Birds also leave calling cards, but usually not the paper kind. They can leave messes on your patio, driveway and outdoor furniture. And with their messes comes seeds they’ve eaten. Most seeds need the acid in the bird’s stomach, plus the grinding action of the gizzard, to break seed coats. The next thing you know, the bird drops the seed along with a little bit of fertilizer, and you have plants such as poison ivy, honeysuckle and mulberries where you don’t want them.

Attracting bats is another way to reduce insects. Some people are more squeamish about bats than birds, though some get nervous around both. Alfred Hitchcock didn’t help. Bats work at night, so many of us don’t see them unless we catch something swooping around our yards at night. If you have lots of mosquitoes, try for bats.

Six-legged help

You also need to bring the good insects into the yard.

This is a double-edged sword. Many good insects that feed on bad bugs look scary, move slowly, and are often crushed underfoot. Some, like ladybugs and praying mantis, have a good reputation so we leave them alone, though counting on praying mantis to control pests only works as long as the pests are there. Otherwise, it’s like “The Hunger Games,” with a sole survivor.

Most of the world’s evil mites are controlled by good mites, except indoors where the good ones can’t survive. Not all the good insects feed on other insects. Monarch butterflies and honeybees won’t cannibalize other insects. In fact, the vast majority of insects never cause any problems.

From the landscape perspective, the best way to attract anything good comes down to one word: diversity. The more plants of various types you put in the ground — almost approaching a jungle appearance but more managed — the wider range of creatures you’ll attract to your yard.

And the wider range means fewer of those deemed pests.

The more you approach a monoculture, such as acres of lawn, the more you can count on insect problems. You can see it’s a tight rope. When do you have too many plants? When do you have too few?

It’s a matter of personal preference, but as long as your yard isn’t encroaching on your neighbors, your family members don’t mind, and you can see the house, keep planting.

David Robson is a specialist with University of Illinois Extension. For more gardening information or for your local extension unit office, go to www.extension.uiuc.edu/mg.