Get to Know These Beneficial Bugs
Welcome These Beneficial Predators into Your LandscapeClick thumbnail to view full-size
If you've got ‘em, don’t swat ‘em.
Chances are none of us would stomp a ladybird beetle with our garden clogs. We probably wouldn't smack at a shimmering dragonfly as it skittered across our koi pond either. But we might be tempted to squash an assassin bug, swat a hover fly, or scrape lacewing eggs off the leaves of our favorite plant.
Squashing "nasty bugs" just comes naturally to most of us. But it isn't always the right thing to do. Lots of less-than-lovely-to-look-at insects are actually beneficial predators.
Beneficial predators are good for your home landscape.
Although they’re not pretty, bugs like the ground beetle, the bigeyed bug, the spined stink bug, the assassin bug, the damsel bug, the hover fly, and the lacewing help keep our landscapes looking good by eating pests that might otherwise damage or destroy flowers, vegetables, and fruit crops. Because they attack and kill garden pests, they're called beneficial predators.
Learn to recognize beneficial predators so that you don't mistake them for pests.
Descriptions of seven of these helpful creatures follow, as well as a list of the problem pests they combat. Get to know what these Plain Janes look like during every stage of their lives so that you can make them welcome in your home garden. Doing so is just one aspect of Integrated Pest Management (IPM), a practical and more ecologically friendly way to deal with problem pests than traditional chemical methods.*
1. Assassin Bugs
During adulthood, assassin bugs can reach up to 1/2-inch long. They're usually brown or black, with narrow heads, strong beaks, and relatively big eyes.
Two common species include the leafhopper and the spined assassin bug. Leafhoppers can be red, brown, or a yellowish-green. They have large, sticky front legs that they use to grab and hold their prey. Spined assassin bugs are usually reddish brown or brownish black with front legs that are covered in spines.
Because they are indiscriminate killers, assassin bugs sometimes feed on other beneficial predators, including ladybird beetles and bigeyed bugs. Nevertheless, they attack and eat plenty of pests, too.
Favorite Meals: Aphids, caterpillars, Colorado potato beetles, Japanese beetles, leafhoppers, and damsel bug eggs are just a few of their favorites.
2. Bigeyed Bugs (Geocoris)
In the home garden, bigeyed bugs are most likely to be found in fruit trees. Adults are black or gray, and about 1/8 to 1/4 inches long. As their name suggests, they have very prominent eyes. Bigeyed bug eggs are either pink or light yellow, and they're ribbed.
Favorite Foods: Bigeyed bugs prey on pests that attack fruit, including lygus bugs, aphids, leafhoppers, and spider mites. As nymphs and adults, they kill pests by sucking out their body fluids.
3. Damsel Bugs (Nabis)
Assassin bugs and damsel bugs resemble each other; however, damsel bugs are smaller, only 1/8 to 3/8-inch long. Despite their small size, they're voracious. And they continue to feed on pests midsummer, when many other beneficial predator populations drop.
Damsel bugs primarily eat immature insects and insect eggs. They also eat mites at every stage of their development--from mite eggs to adult mites.
Favorite Snack: Pests that prey on fruit trees. If you have an orchard, damsel bugs can be your most faithful workers. They begin eating fruit tree pests in early March and--if you're nice to them--they'll keep munching all summer long.
4. Ground Beetles
There are many types of ground beetles (carabids)--all of them beneficial, including the common black, the boat-backed, the tiger, and the European ground beetle.
Most adults are 1/8-inch to 1¼ inches long. Although their shape varies, they are usually lozenge-like, with tapered heads. Black or dark brown is the most common color; however, some ground beetles are purple, metallic green, or multi-colored.
All ground beetles can move quickly when they want to, and they have prominent legs and antennae.
Favorite Foods: They eat a variety of garden pests, including cutworms, housefly maggots, snails, and slugs.
5. Hover Flies (aka Syrphids or Flower Flies)
As adults, hover flies (also called syrphids and flower flies) resemble bees. Like bees, their abdomens are striped yellow and black or white and black, and they travel from flower to flower, feeding on nectar and pollinating crops. Unlike bees, they don't sting, and they only have one set of wings.
If any of your plants are infested with aphids, consider yourself lucky if you see hover flies in the vicinity. Adult females lay eggs near aphid colonies. When their eggs hatch, the larvae (maggots) feed on the aphids. Hover fly maggots can be green or brown, and some have black markings.
Favorite Food: Hover fly maggots enjoy snacking on mites and caterpillars, but their favorite food is definitely aphids.
Hobbies: As adults, hover flies won't combat the pests in your yard, but they will pollinate your flowers.
Lacewings are voracious predators. They destroy all sorts of common garden pests at a great rate, particularly during their larval stage, when they'll eat 200 per week. Some of the pests on their hit list include aphids, thrips, spider mites, whitefly, mealybugs, leafhoppers, and pest caterpillars.
Lacewing larvae are rather pedestrian looking, with bristly yellow-brown bodies. They have long, curved mouthparts that are perfect for seizing prey, injecting paralyzing venom, and sucking out body fluids.
Adult lacewings and lacewing eggs are unique in appearance, which makes them easy to spot. The eggs are bright white, and they are laid at the ends of silken stalks about a 1/4-inch long. Adult females attach them, either individually or in clumps, to leaves and stems.
Adults lacewings are notable for their thin, veined wings which extend beyond their bodies. They're eyes are large, too, especially compared to their tiny heads. They may be brown or green.
Favorite Meal: Although they like to eat aphids, lacewings also snack on other small insects, like caterpillars.
7. Stink Bugs (Spined/Rough Shield Soldier Bugs)
Some stink bugs are pests themselves, but not spined and rough shield ones. They can truly be soldiers in your garden, attacking and killing over 100 species of insect pests that harm plants. Adults are only about 1/2-inch long. Nymphs are shorter, and they have shorter wings. Both adults and nymphs, however, have no problem attacking pests much larger than themselves. Once they have prey in their grip, they suck out its body fluids.
Favorite Food: Spined stink bugs love caterpillars, including canker-worms and gypsy moth caterpillars.
*More Information About IPM
Want more information about IPM strategies for your garden? Read these fact sheets from the Environmental Protection Agency (EPA). Or check out IPM for Gardeners: A Guide to Integrated Pest Management at Amazon.com.
Beneficial Predators & Their Prey
Prey (Garden Pests)
Aphids, leafhoppers, caterpillars, & other beneficial predators
Lygus bugs, aphids, leafhoppers, & spider mites
A variety of pest eggs & nymphs, as well as mites at all stages of development
A variety of insect larvae & pupae as well as other garden pests, such as snails & slugs
Aphids, scale insects, & thrips
Aphids, mealybugs, spider mites, leafhoppers, and more
Over 100 pest species, including gypsy moth caterpillars
Good Bug Books
Includes descriptions and photos of both beneficial predators and garden pests.
If you want to adopt an IPM approach in your garden, BUY THIS BOOK. Like IPM, it's sensible and practical, and it will help you reduce the risk of pest problems in your home landscape.