Non-toxic precautions can help keep lawn and garden pests from bugging you

August 21, 1993|By Ann Egerton | Ann Egerton,Contributing Writer

Insects and other creepy crawly creatures have a field day in the garden (and the lawn, the orchard, the farm, the woods - anywhere green things grow) every summer. Most of us have experienced the frustration and disappointment of losing vegetables and flowers ` from individual plants to entire crops -to various voracious insects and other members of the phylum Anthropod. Scientific nomenclature aside, to mournful gardeners they're just plain pests or bugs.

Samples of damage in the garden include:

Withered and unproductive vegetable plants, thanks to the cutworm that has sawed through the base of the plant.

Gaping holes in petals, leaves or fruits of any plant that strikes a Japanese beetle's fancy.

Exhausted, non-producing tomato or other vegetable plants, thanks to the white fly whose larvae have sucked the plant to death.

Wilted or distorted plants, courtesy of scale, a multicolored shell left behind by any of the 1,700 scale species.

Holey leaves and flowers, dinner for slugs and snails at night.

Trees, especially oak, damaged by gypsy moth caterpillars.

And, unfortunately, much more.

But, according to "Tiny Game Hunting," (Bantam Books, $8.50) a book about pests and pest control, less than 1 percent of the world's 10 million species of insects are considered pests, and most have predators or parasites who are eager to eat them.

Like many things in life, some pests are both good and bad, usually depending on their cycle in life - witness the butterfly and moth, which chomp leaves and stems during their larval (caterpillar) stages and then, as beautiful adults, pollinate flowers and serve as hearty meals for birds. And while Ogden Nash may have observed that God made the fly but forgot to tell us why, the Tachinid fly, which resembles a large and hairy housefly, parasitizes insects, especially caterpillars (including gypsy moths).

Garden pests are a vital part of the food chain. The ugly slug is food for ducks and some snakes, and their larvae are dinner for fireflies, which feed the birds; the 4,000 species of aphids, which love buds and tender leaves, feed parasitic wasps; and white fly is a staple for the lady bug, considered by many to be the best pesticide on legs.

Great success in killing pests can throw the food chain out of whack. Even the book "Controlling Lawn and Garden Insects," ($1.98) published by Ortho, a garden supply company owned by Chevron Chemical Co., counsels: "To avoid killing too many beneficial insects, it's best to use insecticides only when pests get out of control and then only on infested plants."

Some pest control may be necessary; so is coexistence. Many organic supply houses do nicely selling such beneficial insects as lady bugs, lacewings and praying mantises.

What bugs Maryland

According to Dr. John Davidson, an entomologist at the University of Maryland, our enemies in the garden are either chewers (leaf beetle, flea beetle, Japanese beetle, May and June beetle, Colorado potato bug, caterpillar) or suckers (mite, aphid, thrip, scale insect, white fly). He says this year, so far, has not been too bad for garden pests.

"Well, maybe the mites have been bad," he hedges. He goes on to say spider mites have attacked several kinds of shrubs, such as burning bush and butterfly bush, and small trees, such as dogwoods.

"They suck the chlorophyll out of the leaves causing them to turn brown and drop prematurely," he says. Mites are usually kept in check by their natural predators. But this year, the heat has caused mites to reproduce faster than those who find them a delectable snack, he explains.

Also wreaking havoc this year are lace bugs, says Dr. Davidson. "They're bad, particularly on azaleas." These lace-winged creatures also suck the chlorophyll out of leaves.

The other pest that's taking a noticeable bite out of our landscape this year is the bark beetle. "They attack white pine," says Dr. Davidson. "Because of this year's dryness, the pines can't make enough pitch, so they can't repel the beetles that bore into their bark." Pitch is a sticky substance in the trees that serves as a natural protector. Beetles get caught in it and die before they do damage.

"These are key pests," says Dr. Davidson. "They come every year. Most years they're a little less serious. They might brown 10 percent of the leaves instead of 80 or 90 like this year."

The good news from Dr. Davidson? "Gypsy moths are not as bad as usual."

The Japanese beetle problem

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