By Erin Marissa Russell
Ready to find out how to get beneficial insects to fly by your garden—and learn to identify them on sight? This guide explains why some insects are more welcome than others in the garden. We’ll teach you what to do to bring in the insects that will help your garden flourish. And once you’re done reading, you’ll be able to tell bad bugs and beneficial bugs apart as well as learning to identify them by sight.
The small assassin bug can put a big dent in the pest population of your garden. These bugs live more than one season and eat leafhoppers, beetles, and caterpillars. Assassin bugs are black, brown, or red, measure up at under an inch long and can be spotted by their narrow heads with beady eyes and needle-like beaks with three sections. Their front legs are large for grappling with prey. Their eggs are laid in distinctive “raft” formations, in batches of 10 to 25 or even more, and are protectively coated in a sticky substance.
Damsel bugs eat lots of garden troublemakers: soft-bodied insects, aphids, leafhoppers, caterpillars, thrips, mites, and spider mites. Damsel bugs grow up to half an inch long. You’ll see them come out of hibernation in April or May, and they’re visible outdoors until the fall. Damsel bugs most commonly come in shades of yellow, gray, or brown. They are thin-bodied insects with long heads and antennae and enlarged front legs with which they clasp their prey.
There are many varieties of ground beetles, but most come in dark shades and feature prominent eyes and thin, thread-like antennae. All live on the ground, and they range in size from an eighth of an inch to one inch long. They eat ants, cutworms, earthworms, maggots, slugs, and other beetles. You won’t see these often, as most ground beetles are nocturnal.
Hoverflies look more like wasps than flies. They have the striped body of a wasp, in bands of yellow and black. They even imitate the behavior of wasps—except that wasps seldom hover. Gardens depend on hoverflies for pollination, and in their larval stages, they feed heavily on aphids, mites, thrips, and other small garden pests.
Lady bugs, also called lady beetles, are among the most recognizable insects in the garden. They’re known for their red hue and black markings, but mite-eating and Scymnus ladybugs are shiny black. Other colors may include orange, pink, or yellow, and not all ladybugs have spots. Immature ladybugs have elongated black bodies with yellow-orange markings. Seeing ladybugs in the garden is a sign that the system is healthy and functioning well. They eat aphids, spider mites, and scale insects.
Lacewings are known for their thin, pale green bodies and delicate, lacy clear wings. However, similar-looking insects that are smaller and brown are another variety of lacewing. The larva, called aphid lions, hatch from eggs laid singly on top of a long stalk. They eat aphids, small beetles, and caterpillars.
Pirate bugs will curtail the population of spider mites, rust mites, aphids, leafhoppers, mealybugs, and thrips. They’re oval in shape and tiny—one twelfth to one fifth of an inch long. Pirate bugs come in black or shades of purple and have white markings. They appear in March or April, persisting through summer. Young ones and adults alike can eat up to 30 or 40 mites and aphids each day.
A praying mantis in your garden is a stealthy predator that will set up shop and take out insects that can cause trouble. However, these guys eat a little of everything, so they are prone to making dinner of other beneficial insects, like bees and other pollinators. At between one and four inches long, they’re some of the largest insects you’ll see. Look for them between midsummer and the middle of autumn. You’ll also know them by their pale green color, triangular head, and long, jointed legs that fold into the “praying hands” pose they’re named for.
Predatory mites often go unseen due to their tiny size of just one fiftieth of an inch. They are larger, rounder, and faster than the mites that are their prey. They eat the mites that can plague your garden, including spider mites, as well as thrips and insect eggs. Provide good hiding places for predatory mites to increase their presence in the garden. They conceal themselves on the undersides of plant leaves that have hairs, chambers, or pits.
Spiders generally fall into three hunting categories: ambushers that lay in wait for their prey, active hunters that chase other insects, and spinners that create webs to catch their victims. All varieties of spiders eat pest insects, such as aphids, beetles, caterpillars, and leafhoppers.
If you ever handled a stink bug as a child, you know why they got their stinky name. Some species of stink bug make a meal out of other garden insects. Although even predatory stink bugs are known to take a bite out of a plant now and then, they won’t eat enough of your plants to damage them. That said, the types of stink bugs that are not predatory can damage your garden, so be sure to positively identify which type you’re dealing with before you decide whether to let them be or kick them out. Gardeners in the Pacific Northwest may have heard that there are no harmful stink bugs near them, but this has changed with the appearance of the marmorated Asian stink bug. Types of stink bug vary by region, so do a search for stink bugs in your area to compare and contrast.
These gardener allies look like oversized black houseflies, but they make short work out of caterpillars in the garden. They lay their eggs on the caterpillars, and when they hatch, they burrow inside the caterpillars’ bodies. There, they consume the caterpillars’ organs, eventually killing the caterpillar when the tachinid fly emerges to pupate.
Wasps and Hornets
Though we often run the other direction if we see a wasp or hornet in the garden, in reality they’re beneficial bugs. They’re known for searching through plants to find caterpillars, dispatching them, and transporting them to their nests to feed the baby wasps. The exception is yellowjackets, whose aggressive behavior makes them more risky than helpful. In the Pacific Northwest, the European paper wasp is a non-native species that is another aggressive type. It will be obvious if one of these wasps is in your yard by their behavior. Remove the nests of European paper wasps from the garden to discourage them from setting up shop in your yard. Their territorial, assertive tendencies make them a stinging risk to both people and pets if their nest is nearby. Yellowjacket nests may be underground or inside the walls of a structure, and professional help will be needed to remove them.
To Attract Beneficial Insects
There’s a lot that gardeners can do to make their yard a more comfortable and inviting place for these beneficial insects.
- Cut down on chemical insecticides. Simply narrowing the spectrum and using these less frequently will have an effect on your beneficial bug population, but the smaller the amount of chemical pesticides you use, the bigger the benefits you’ll see.
- Avoid bug zappers that use light to lure in mosquitoes and electricity to kill them. These actually kill more beneficial bugs than pests.
- Plant shrubs, bushes, or gardens instead of cultivating wide expanses of lawn. In addition to providing pollen and nectar, these plants also provide hiding places and habitats that lawns simply don’t. Leaving some leaves and plant debris scattered underneath bushes goes even farther to make beneficial insects comfortable.
- Focus on growing native plants to have the maximum effect on your insect allies. Leave some of the native plants undisturbed in the garden over fall and winter to give beneficial insects a space to overwinter.
- Aside from native plants, you can grow these varieties, which beneficial insects prefer: basket-of-gold, chamomile, coriander, dill, edging lobelia, European goldenrod, fennel, lavender, masterwort, moon carrot, sedum, sweet alyssum, veronica, and yarrow.
- Plan your garden so plants go into bloom in succession so you’re providing pollen and nectar all season long.
- It’s more effective to attract your local beneficial insects and convince them to make your garden their habitat than it is to bring in purchased predators, such as ladybugs or praying mantises. Purchased bugs tend to keep moving once released, even if prey and pollen are widely available, and they may not be from your area, so the local conditions may be harmful to them.
When it comes to insects, it’s vital that gardeners know which ones are friends and which ones are foes. After all, you’ll want to know for sure whether the bugs you see are signs of an impending infestation or simply pollinators making their rounds of the neighborhood. Not only that——you’ll know exactly how to reel in those beneficial bugs, making yours the smartest garden on the block.