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Published on 06/26/03

Is that a good bug or a bad one?

By Mike Isbell
University of Georgia

"But it's a caterpillar," my daughter Jordan said as we looked over the muscadine vine in our yard. "And it's cute."

Cute, my foot.

That caterpillar was a tomato hornworm. It can eat my muscadine vine faster than my friend Willie can eat a pot of turnip greens. And it's got plenty of help -- Japanese beetles. They're munching away on my vine and the little developing fruit, too.

I'm killing every one of them.

Earlier in the season, as the vine began to put on new leaves, I battled a horde of small, leaf-eating caterpillars called Eastern grape-leaf skeletonizers and hundreds of sap-sucking aphids.

Protecting grapes

But I got rid of all those little pests. Now if I can keep these insects at bay, I should have a good crop of muscadines.

Insects are among the oldest, most numerous and most successful animals on earth. It's estimated that more than 100,000 species live in North America. In your backyard and mine there are probably 1,000 insect species at any time.

It's lucky for us that only 3 percent of all insects are pests. Those 3 percent can cause trouble enough, sometimes reaching astonishing proportions. Some bite us, sting us and act as disease vectors. Some destroy stored foods and other products.

And some eat our crops, like my muscadines.

Insects eat their food in a variety of ways. Some are chewing bugs like the tomato hornworms and Japanese beetles I'm dealing with now. Another group, which includes aphids, feed on growing plants by piercing the plant tissue and sucking sap from the cells.

Inside job

A third group feeds from inside the plant. How do they get there? Well, their mamas can put them in there, where they hatch -- or they can hatch first and then eat their way inside.

Sounds like a Stephen King monster movie to me.

Thankfully, not all insects are bad.

Some aid in the production of fruits, seeds, vegetables and flowers by pollinating the blossoms.

Parasitic and predator insects destroy the ones that harm our crops, while other insects destroy various weeds the same way some injure crop plants.

Insects improve the physical condition and fertility of our soils by burrowing throughout the surface layer.

And just think what this place would be like if insects didn't act as scavengers and devour the bodies of dead animals and plants. And what if they didn't bury carcasses and dung?

But that's another story. For now, I'm getting rid of tomato hornworms and those darned Japanese beetles.

(Mike Isbell is the Heard County Extension Coordinator with the University of Georgia College of Agricultural and Environmental Sciences.)

Mike Isbell is the Heard County extension coordinator with the University of Georgia College of Agricultural and Environmental Sciences.