While you may not take much notice of the insects in your garden, a closer look yields an intricate ecosystem of teeming plant and insect life. Though pollinators are certainly the most popular beneficial insects, there are a medley of other insects that prey on pests and reduce the need to resort to chemical pesticides.
In contrast to pesticides, beneficial insects present the ideal organic control for sustainable solutions long-term. Casual gardeners may be unaware of the ‘pesticide treadmill’ phenomenon, which accounts for between 500 and 1000 species of insect and weed species that have developed pesticides resistance since 1945. Below is a list of common beneficial insects to keep an eye out in the garden, and what steps you can take to attract them.
There are three main types of beneficial insects you may encounter: pollinators, predators, and parasites.
Pollinators – Include butterflies, moths, and flies; responsible for fertilizing flowers and contributing to their abundance; some, such as hoverflies, are also predatory
Predators – Recommended for organic pest control, as they prey on pests; include ladybugs, lacewings, and praying mantises
Parasites – Target pests by depositing their eggs on host insects, which will hatch, attack, and eventually kill it; includes wasps, flies, and a few varieties of beetles
The bright appearance of the ladybug belies a voracious appetite. Interestingly, they are not a true bug and are actually beetles. An adult ladybug can consume up to 50 aphids a day and up to 5,000 aphids in their lifetime. In addition to aphids, they also consume whiteflies, mites, thrips, the Colorado potato beetle, and other soft-bodied insects. Beware of imposters such as the Mexican bean beetle, which feed on lima beans and soybeans and are considered serious agricultural pests. This lookalike appears slightly larger, with an odd, orange tone to its carapace. Ladybugs are attracted to nectar producing plants such as milkweed, cosmos and zinnias and herbs such as dill, lemon balm, and mint.
Adult lacewings feed on nectar and pollen, but their larvae will feed on soft-bodied pests, particularly aphids, caterpillars, mealybugs, and whiteflies. Active during nocturnal hours, these fairy-like, mesh-winged insects can release an unpleasant odor when handled, giving rise to the name stink flies. Their larvae, which resemble alligators, prey on pests using pincher-like mandibles. Aim to attract lacewings if you frequently encounter aphids, whiteflies, or pest caterpillars. While you can purchase lacewing eggs commercially, you can attract them naturally by growing native flowers, tall grasses, or perennials with flat flower heads, such as these in the aster and parsley family.
Similar in appearance to assassin bugs, damsel bugs are abundant in gardens and commercial fields where cotton and soybean are grown. They seek low-lying plants where they prey indiscriminately on a wide range of insects, including common agricultural and garden pests. To encourage damsel bugs to the garden, select plants that will provide hiding spaces, such as ornamental grasses, fennel, mint, and goldenrod. Damsel bugs, who belong to the order Hemiptera, which includes assassin bugs, stink bugs, and plant bugs, are not to be confused with damselflies.
True to their name, assassin bugs ambush their prey by piercing its body with a dagger-like mouth part known as a rostrum, which injects a paralyzing venom to incapacitate it. Often appearing in colors of black, brown, or rust orange, assassin bugs have long, spindly legs and elongated bodies. Apart from the occasional bite, there is no cause for concern. Kissing bugs, a type of assassin bug, are considered pests because they feed on the blood of vertebrates and may be vectors for the deadly Chagas disease. However, the two species most commonly responsible are usually found in rural Central America instead of the US. An aggressive insect, the assassin bug devours flies, beetles, caterpillars, leafhoppers and aphids. Commonly found in vegetable gardens and ornamental flower beds, many are attracted to light, so consider installing some light fixtures.
Dragonflies and damselflies
Dragonflies and damselflies have been on earth since time immemorial – they are among the oldest winged insects. If you have ever been to a pond or river, it is likely that you have seen those gossamer-winged insects gliding over the water. Requiring a clean, freshwater source, they depend on aquatic environments to reproduce and have a reputation for eating mosquito larvae. Damselflies, which tend to be smaller and less robust, rest with their wings closed vertically, instead of apart. Like dragonflies, damselflies are vital to the aquatic ecosystem and eliminate a variety of bothersome insects. For those wanting to attract dragonflies to the garden, be cautious of shallow pools of stagnant water, which can become breeding grounds for mosquitos.
A vicious and fearless predator, the robber fly will feast on a copious amount of insects, from grasshoppers and wasps to beneficial pollinators such as butterflies and bees. For this reason, they are considered of dubious benefit, and gardeners should not take active means to attract them. As the name suggests, robber flies ambush unsuspecting victims in mid-air, injecting paralyzing toxins that liquify their insides. At first glance, they can resemble bees or dragonflies, but can be differentiated by their distinctive hump-shaped abdomens.
Praying mantises are known for their strange, distinctive appearance and generalist diet. Although not commonly sighted in gardens, contrary to popular belief, they are not considered an endangered species. Mantises do prey on pests such as aphids, crickets, and moths, but they do not make the distinction between beneficial insects and pests, and will eat them as well. Larger species have been known to eat frogs, lizards, small birds, and even snakes. If you spot one, you can gently pick it up and examine it.
Though ground beetles can vary considerably in color, the most common are mottled black, brown, or iridescent green. Once night falls, they scurry out in search of snails, slugs, cutworms, and squash bugs. Some species also consume weed seeds. In the day, they tend to hide under stones and leaves, inside mulch, rotting wood, and other decaying debris. To attract ground beetles, you can create a small beetle refuge in a raised garden bed. Incorporate cover crops, native perennials, and ornamental grasses and add a layer of mulch, along with some rocks and logs to provide hideouts.
Big-eyed bugs derive their name from their wide-set bulging eyes, which give them a humorous appearance. These tiny bugs hunt a broad range of small prey, including aphids, mites, cabbage loopers, thrips, and small caterpillars, using their piercing proboscis to such juices from their prey – both adult insects and larvae have similar diets. When prey is scarce, they can survive on nectar and honeydew. Though they do occasionally suck on plant juices, they are not considered harmful. Invite big-eyed bugs to the garden by planting cosmos, marigold, goldenrod, and soybeans.
Though worms are technically not insects, they are underrated organisms that are beneficial to the soil in your garden. One of the most popular uses for earthworms is composting, where they are used to enrich and aerate the soil. Vego Garden’s in-ground worm composter makes it easy to compost kitchen scraps without the hassle and smell of traditional composting systems. As the worms digest organic matter, they produce worm castings, which can repel chewing or sucking insects like aphids and plant bugs as well as create effective fertilizer for your plants.