Wilting leaves, holes in foliage, rotting veggies, sticky substances over your neat vegetable rows? It's enough to make a grown gardener weep. Did you ever wish you had a large staff who would help you protect your vegetable garden from all those insect pests? It's not that hard to enlist a cast of thousands to help your crops thrive and grow, whether you have a container garden or one in your backyard, and these assistants don't even want a salary. These helpers are called beneficial insects. It may seem odd to bring in insects to help control other insects, but that's the natural world for you. Most every type of living creature is food to another, and, by encouraging the predator insects to take up residence in your veggie plot, you'll reduce the damage from the worst garden pests. Plus, enlisting beneficial insects as your bad-bug posse means you don't have to spray toxic chemicals on your growing vegetables.
1) Ladybird Beetle
The rock-star of the beneficial insects is the ladybird beetle, but, like all celebrities, it's better known by a stage name: ladybug. Even the youngest gardener will recognize the cute, rounded shape of this common beneficial insect. The ladybug may look darling but it's also a voracious predator of aphids, scale insects, and mealybugs, all of which attack your vegetable plants.
You may know that most insects have a larval stage as well as an adult stage. It's important to learn to recognize the larval stage of the ladybug, since ladybird beetle larva also are beneficial munchers of aphids and bugs. In fact, one ladybug larva can eat up to 40 aphids an hour, for a total of some 500 aphids before maturing into an adult. On the other hand, an adult ladybug can eat some 5,000 aphids in a lifetime. So, keep your eye out for the larva that looks like a tiny alligator, ½ inch long. Its base tone is black but it has spines and bright spots on its small body. And remember, to kill a larva is to kill a ladybug.
How to Attract: Attract these helpful insects into your garden by planting some of their favorite flowers. These include dill, dandelion, fern-leaf yellow, and yarrow.
2) Green Lacewing
The bigger the appetite of a beneficial insect, the more assistance it offers in the garden. One helpful hungry insect is the green lacewing that devours aphids, caterpillars, mealybugs, scales, thrips, and whiteflies. Yes, this lovely insect can really chow down despite its delicate appearance. Only ¾-inch long, the green lacewing has a pale green body bearing four transparent wings.
The larva stage is equally if not more helpful in the garden, so don't kill them. They are ½ -inch long, and pale brown with darker brown markings. You can recognize them by their unique, curved jaws, just right for picking off prey. Like teenagers, they are absolutely starving all the time and will happily eat lots of bugs you do not want in your veggie patch, the entire range of prey of the adult lacewings plus small caterpillars, leaf hoppers, and insect eggs.
How to Attract: Plant dill, angelica, coreopsis, golden marguerite, cosmos, and sweet alyssum and add a supply of water for them. Lacewing adults gravitate at night toward outdoor lighting, so solar lights in your garden is a good idea.
3) Soldier Beetles
If you are growing cabbage or corn in your garden, you may want to welcome soldier bugs. These predator bugs look more menacing than other beneficial insects. They are brown or yellow with many black spots and spined, with a weapon-like proboscis. But once you understand what they do with that proboscis, you may learn to love the soldier bugs.
Voracious predators, spined soldier bugs attack some of the most damaging garden pests, including the European corn borer and corn earworm, Gypsy moth caterpillars, cabbage looper, cabbage worm, flea beetles, Colorado potato beetles, fall army worms, beet army worms, diamond back moth, cotton boll worm, and Mexican bean beetle. These agile insects dash about, racing up plants or flying among them to locate prey. Once prey is located, the soldier bug inserts its proboscis and sucks out the victim's juices. All told, the soldier bug preys on some 100 different pests, making it a very effective helper in gardens and greenhouses.
Again, you'll need to be on the lookout for the other stages of life of the soldier bug. The female adults lay clusters of barrel-shaped eggs on stems and leaves, up to 1,000 during their lifetime. The eggs can be gray, cream or gold. These develop into nymphs that stay near the egg clusters and eat insect pests too.
How to Attract: If you are ready to invite soldier bugs to help win the war on pests in your veggie garden, here's how to do it: plant permanent beds of perennials to provide shelter for them.
4) Minute Black Scavenger Fly
Minute black scavenger flies do not eat any other insect, but you still want them in your backyard. These tiny insects are extremely useful in the compost heap where you may see them gathering in great numbers. They do no harm to humans, pets or other plants, but really speed up the decaying process required for compost.
How to Attract: If you don't have a compost pile, starting one is the best way to attract these flies. And a compost pile — where you place garden detritus and kitchen peelings — is a terrific and cheap way to enrich your vegetable garden soil with organic matter. A compost doesn't have to involve an expensive container or even fancy fencing. Just start a pile of organic garbage in a corner of the backyard, add water, and turn it occasionally. As it "composts," the garbage turns into brown, soil-like matter that can replace the bagged compost you purchase at garden stores. Worked into soil, it provides essential nutrients for your vegetables and also significantly improves soil drainage.
5) Damsel Bugs
Don't let their slender bodies fool you. Damsel bugs eat a lot, devouring aphids, small caterpillars, mites, cabbage worms, leafhoppers, thrips, and other garden pests. They are also predators of moth eggs, corn earworm, European corn borer, imported cabbage worm, army worms, small sawfly larvae, tarnished plant bug nymphs, asparagus beetle, and Colorado potato beetle eggs and nymphs. A young damsel bug only eats one egg or aphid per day, but they down dozens of eggs or prey daily as they develop into instars (their teen stage) and adults
Recognize damsel bugs by their tan color. They look like small, smooth assassin bugs, with enormous eyes and very long legs for their size. The front set of legs are thicker than the back and lined with spines to trap and hold their prey. And yes, they too suck out the body contents with their mouthparts.
How to Attract: You can find these predator bugs in a variety of crop situations. If you live near an alfalfa field, for example, you can catch some with a sweep net and transfer them to your vegetable garden area. Alternatively, attract them by planting fennel, Peter Pan goldenrod, spearmint, and caraway.
6) Pirate Bug
You can hardy see these little bugs, and their small size explains why many refer to them as "minute" pirate bugs. Even mature adults (black with white diamond patterns) are about 1/12 of an inch, while the wingless yellow-brown nymphs are almost invisible. But despite their small size, both nymph and adult pirate bugs eat and eat and eat. And what they eat are the soft-bodied insects you want OUT of your vegetable garden, including aphids, spider mites, thrips, caterpillars, and their eggs.
Hate spider mites? One adult pirate bug takes out over 30 spider mites per day, using its thin beak as a sharp straw. They insert the proboscis into the prey and suck it out like a smoothie. And these small predators are really fast, zipping up behind insect victims and clasping them with their front legs while they pierce them. They are one of the first predators to hatch out in spring and you may get several generations of them in one growing season. Look for pirate bugs on their hunting grounds, that is, on plants like corn, beans, soybeans, strawberries, tomatoes, and grain crops as well as nearby flowers.
How to Attract: They can be attracted to your backyard if you grow their preferred habitat plants, like vetch, sweet clover, alfalfa, and daisies. It's also a good idea to let spring and summer flowering weeds dwell in a garden corner since pirate bugs like them too. To take these bugs on as garden workers, you should avoid broad spectrum pesticides or soil-applied systemic pesticides, which can kill these helpful insects.
7) Parasitic Wasps
Another small but lethally effective predator bug is the parasitic wasp, so tiny you may not even spot them. They are usually dark with four transparent wings, and under ½ inch long. Because they are tiny and the fact that there are more then 15,000 species, they are tough to identify. But if they are on your garden "staff," you will benefit greatly from their presence.
The way these wasps kill insect pests is unique, fascinating, and the stuff of nightmares. The female adults of some species inject their eggs into their prey. As the larvae develop inside the "victim," they literally devour the prey alive, eating it from the inside out. The behavior of other species is slightly different. Brachonid wasps lay their eggs on the backs of their prey, and the larva perform the same feat from the outside in.
Before you start feeling too bad about this, note that Brachonid wasps lay their eggs in tomato hornworms, very destructive pests in the veggie garden. If you see a white cocoons on the worm's back, do not touch. The larva will do your work for you, then hatch into adult wasps who continue the cycle, doing their best to keep your tomato patch free of the hornworms. Other species parasitize corn borers, gypsy moth caterpillars, grasshoppers, Japanese beetles, Mexican bean beetles, squash bugs, and green stinkbugs.
How to Attract: You can summon these garden friends to your backyard by planting the right flowers. Try putting in nectar plants with tiny flowers like yarrow, lemon balm, wild carrot, dill, and parsley.
8) Ground Beetles
Now for the night shift. Your garden is hard at work, day and night, producing your summer eating, so your security staff needs to work at night too. Bring in the ground beetle for this important role. Worried about nematodes? Caterpillars? Slugs? Silverfish? The entire ground beetle family — from larvae to adults — will eat these insects for you, and more. And they are active at night.
The nocturnal ground beetle is a voracious predator of pest insects like cutworms and cabbage maggots that lurk on and under the soil in your garden. One beetle, all by itself, can devour over 50 caterpillars. But that's not all. These bugs are big and tough and hungry enough to deal with slugs and snails as well.
How to find out if you already have ground beetles? Turn over a log or a rock and watch for big, black, clumsy beetles scurrying for cover. They hide by day and hunt by night — a perfect combination for your veggie garden. These beetles regularly are ranked among the top 10 beneficial predator bugs a garden can have. Nearly all of the thousands of species of ground beetles in North America prey on other invertebrates, usually pests.
How to Attract: A few fallen logs left in place might help, but you can also get these bugs working for you by putting in a large selection of perennial plants and shrubs to offer for stable habitats, or use white clover as ground cover.
- Thoughtco: Worst Vegetable Garden Pests
- Garden Lesson: Beneficial Insects Garden Pest Control
- Good Housekeeping: Beneficial Insects that Will Actually Help Your Plants
- The Old Farmers Almanac: Beneficial Insects in the Garden
- Missouri Botanical: Beneficial Insects
- Reno Gazette Journal: Master Gardener: Beneficial Insects in the Vegetable Garden
- UMD Extension: Minute Pirate Bugs
- Thoughtco: Ground Beetles
From Alaska to California, from France's Basque Country to Mexico's Pacific Coast, Teo Spengler has dug the soil, planted seeds and helped trees, flowers and veggies thrive. A professional writer and consummate gardener, Spengler has written about home and garden for Gardening Know How, San Francisco Chronicle, Gardening Guide and Go Banking Rates. She earned a BA from U.C. Santa Cruz, a law degree from U.C. Berkeley's Boalt Hall, and an MA and MFA from San Francisco State. She currently divides her life between San Francisco and southwestern France.