Tips, tricks to debugging your garden

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Beneficial insects and the pests they eat

Assassin Bug — Flies, caterpillars, blister beetles

Bigeyed Bug — Leafhoppers, spider mites

Braconid Wasp — Codling Moth, Imported Cabbage Worm, Tomato Hornworm, Cabbage Looper, Aphid

Centipedes — Soil borne mites, larvae of many insects

Damsel Bug — Aphid, Leafhopper, Thrips

Dragonfly — Each dragonfly can eat 300 mosquitoes a day

Ground Beetles — Slugs, snails, Cabbage Root Maggot, many other pests with a soil stage in their development

Hoverfly — Aphid

Ichneumon Wasp — Caterpillars, Imported Cabbage Worm

Lacewing (and related Western North American native Snakeflies) — Corn Earworm, Aphids, many other pests

Ladybug — Aphid, Spider Mite, scale, mealybugs, other soft-bodied pests

Minute Pirate Bug — Thrips, Spider Mite, Leafhopper nymphs, small caterpillars

Solider Beetle — Spotted Cucumber Beetle, Corn Rootworm, Aphid, caterpillars

Tachinid Fly — Caterpillars, Cabbage Looper, Squash Bug, Stink Bug, Tomato Hornworm

Yellow jackets are considered beneficials, too. You may not want them around when you’re eating outside in July, but they are general pest predators (although they prefer grilled lamb).

— Jeff Cox

If you discover that some kind of insect is damaging your garden, what should you do?

The best thing you can do? Keep calm and carry on. The worst thing you can do? Spray your garden with insecticide. Here’s why.

First of all, a little insect damage is actually good for your crops, whether edible or ornamental. It stimulates growth hormones to repair damage and stimulates the plants to produce insect-repelling compounds.

But what if a pest is so numerous that it threatens to destroy your crop? That’s a signal you need to encourage more beneficial insects to live in your garden, the kind that eat pests for breakfast, lunch and dinner. You can invite them in by planting nectar and pollen-producing plants, especially ones with umbrella-shaped flower and seedheads, like fennel, dill, and carrot, even the wild carrots called queen anne’s lace.

Insect scientists also suggest leaving about 10 percent of your garden space planted in whatever happens to grow wild there (except blackberries and poison oak). This will be habitat for native pest-eating insects.

Pests are food for beneficial insects, so by spraying insecticide on your garden, you are wiping out the pests and the good guys. Pests, however, are designed by nature to be the first ones back into a garden that has been sprayed. After all, they eat plants, so the table is set.

Until pest populations build up, there’s not much for beneficials to eat, so they show up last. The result is that your pest problem will be worse than before.

Besides luring beneficials by providing them with food, water and habitat, you can also order them online and release them in your garden. Be aware that it takes time for beneficials to become working members of a healthy garden ecosystem. They won’t cure a pest breakout overnight.

Green lacewings, mealybug destroyers and other beneficials are available locally at Harmony Farm Supply in Sebastopol. Online sources also will ship them to you. Just search “beneficial insects for sale.”

Some caveats about releasing beneficials in your garden. Ladybugs, also known as lady bird beetles, are voracious eaters of small pests like mites and aphids, but the first thing they do when released in your garden is take a cleansing flight to eliminate body wastes built up during processing and shipping. Many will not return to your garden, although some will.

Usually, they are naturally plentiful when insecticides haven’t disrupted the garden’s ecosystem, so if you see some already in your garden, you probably don’t need to release more.

As for praying mantises, avoid them. Yes, they eat pest insects, but they also eat beneficials. So they do as much harm as good.

Instead of insecticides, there are many nontoxic ways to control pests. Floating row covers will keep pests from infesting your crops. For instance, those cute little white butterflies that usually spiral around each other in pairs? They are Imported Cabbage Worm adults, and their larvae are those velvety, squishy, green caterpillars you find on cabbage family members. Row covers over cabbage crops will prevent them from infesting your crops.

Big caterpillars, like the pretty green hornworms with little red tails you find on your tomato plants, can be hand-picked and destroyed if they are causing excessive damage. Otherwise, ignore them, as they are food for beneficial parasitic wasps. Aphids can be washed off plants with a strong jet of water from a hose and they won’t return, although their siblings might.

The main thing to remember is that nature loves biodiversity, and if you have a balanced crew of insects in your garden, pests and beneficials alike will contribute to the garden’s health.

If your crop repeatedly fails because of insect damage, consider buying that vegetable at the store or farmers market and planting something else. Insecticides don’t just kill insects. They make your garden a toxic environment for you and your family, too.

Beneficial insects and the pests they eat

Assassin Bug — Flies, caterpillars, blister beetles

Bigeyed Bug — Leafhoppers, spider mites

Braconid Wasp — Codling Moth, Imported Cabbage Worm, Tomato Hornworm, Cabbage Looper, Aphid

Centipedes — Soil borne mites, larvae of many insects

Damsel Bug — Aphid, Leafhopper, Thrips

Dragonfly — Each dragonfly can eat 300 mosquitoes a day

Ground Beetles — Slugs, snails, Cabbage Root Maggot, many other pests with a soil stage in their development

Hoverfly — Aphid

Ichneumon Wasp — Caterpillars, Imported Cabbage Worm

Lacewing (and related Western North American native Snakeflies) — Corn Earworm, Aphids, many other pests

Ladybug — Aphid, Spider Mite, scale, mealybugs, other soft-bodied pests

Minute Pirate Bug — Thrips, Spider Mite, Leafhopper nymphs, small caterpillars

Solider Beetle — Spotted Cucumber Beetle, Corn Rootworm, Aphid, caterpillars

Tachinid Fly — Caterpillars, Cabbage Looper, Squash Bug, Stink Bug, Tomato Hornworm

Yellow jackets are considered beneficials, too. You may not want them around when you’re eating outside in July, but they are general pest predators (although they prefer grilled lamb).

— Jeff Cox

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