Sometimes, the only way to stop a bad insect is a good insect

Battle of the bugs

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The garden is always alive with a secret life. Insects are a massive and complex subject, and what I hope to do here is just to introduce the concept of good bugs and bad bugs. You have both in the garden, and as in all things the aim is to keep the garden in balance so the good guys win over the bad guys. It’s been a bug-eat-bug world for a long time, and insects have the drill down pat.

A literal mating frenzy is going on just beyond the back porch, with bugs meeting, mating, and devouring one another. If you begin to notice lots of questionable evidence such as something eating the leaves on your plants, boring into the stems of the squash plants, drilling holes into the cucumbers hanging on the vine, and stripping the leaves off your tomato plants overnight, then you may be out of balance in the garden.

Adding a few plants that attract “good bugs” to eat the “bad bugs” may help strike the balance. Some of these may include parsley, cosmos, coreopsis, fennel or dill, spearmint (always grow mint in a pot), sunflowers, candytuft, and cilantro (which is coriander by any other name).

I also let some of my carrots go to seed when it heats up in the garden and they get “woody” as the flowers of the carrot mimic Queen Anne’s Lace, an attractor of pollinators, which grows wild and blooms all around our roadsides in the country. I enjoy observing all the tiny insects this flower attracts to my garden.

This natural predatory process is to be encouraged so you can grow your garden with as little chemical intervention as possible, especially on the foods you grow to eat. Avoiding chemical insecticides that kill pests is a good approach as you wipe out all the “good bugs” too.


Identifying which bugs are good for your garden and which are bad does require a bit of independent study, but here are a few examples of bad bugs:

Tomato hornworm

Manduca quinquemaculata

The hornworm can grow up to four inches long, and I have seen it devour a plant overnight. Its distinct markings include white diagonal stripes, tiny black spots, and sometimes it has little white wasp cocoons — it is the host for the braconid wasp, on its back. The horn at the rear of the hornworm is harmless to humans.

Corn earworm

Helicoverpa zea

Growing nearly 2 inches and varying in color from light green to pinkish brown or black with strips along its body, adults are night-flying moths, yellowish-tan in color with a wingspan of up to 2 inches.

Cabbage Worms

Artogeia rapae

Light green in color, these worms are common in the garden until it is very cold outside. They have a fine yellow stripe down their backs. The adult turns into the common white moth found in most gardens fluttering around the cabbage plants.

All three of these critters overwinter in the soil or on host plants in the pupae stage and emerge as adults when the time is right to lay their eggs. After several days to a week, caterpillar larvae emerge to feed on our favorite veggies for two to four weeks. They then pupate, emerge as adults, and start all over again. There can be as many as four generations a year. All three of these worms are voracious eaters and contaminate what’s left with their feces.

Hornworms prefer tomatoes but will also go after potatoes, peppers, and eggplant. Corn worms plague corn but will also attack peppers, beans, squash, and sunflowers. Cabbage worms eat anything in the cole family including kale, cauliflower, and broccoli.

Control attempts are floating row covers, spraying with neem oil or BT (bacillus thuringiensis), or using natural enemies including soldier bugs, or green lacewings. Green lacewing bugs are more ravenous than teenagers and love aphids, mealybugs, mites, and small caterpillars. The larvae of the green lacewing looks like an alligator with tiny pinchers. Coneflowers are a good host plant for the green lacewing.

What it always comes down to is striking a balance. I would encourage you to observe closely your garden as the hot months settle in. Look for signs of infestation, plant damage, and produce deterioration. Never compost an infected plant: Bag it or burn it and keep your garden space clean of debris. Then see if you can figure out what the root cause is of this problem in the garden. The power of observation is sometimes the best solution.

See you in the garden.


Kathy Slayter is a Greenville Realtor and Clemson-certified Master Gardener who is passionate about growing, cooking and eating her homegrown food. Contact her at kathyslayter@gmail.com.

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