What are Beneficial Insects?

It is best to plant a variety of species in your garden to avoid problematic insects and plagues. Companion planting is the practice of having plants that complement each other. Plenty of harmful species are repelled by specific types of plants. Having a combination of flowers, herbs and vegetables will also bring beneficial insects to your garden. Beneficial insects are likely to appear even before pests, so they need pollen and nectar if you want them to stay.

You can buy some species of beneficial insects, but it is best to attract them naturally by creating the environment they need. Those living in areas with seasons should look for flowers that bloom at different stages of the year. Also, avoid chemical pesticides since they will kill both the good and the bad. If you need to use pesticides, use ones that have little or no residual activity such as horticultural oil, insecticidal soap or botanical insecticides.

Besides having beneficial insects, it is also important to start your garden with good soil. Plant hardy natives, which will grow best in your climate. You may want to keep some weeds in your garden that are attractive to good insects. Just don’t leave plant debris rotting in the garden, since it can bring harmful bacteria and destructive insects. Best to place any plant material that does not have pest or diseases in the compost pile. Affected plant parts must be trashed.

Keep a water source for your bugs, especially during the summer or dry spells, so they can keep hydrated. This is specifically needed for bugs that prey on other insects. Others get their liquid from the nectar or plants they eat.

Insects are not the only beneficial creatures for your garden, other species that make this list are ants, bats, toads, birds, beneficial microbes and viruses. Of the thousands of insects that may live in your garden, only about a tenth are destructive.

The 3 Ps

Predators

Predators eliminate pests by eating them. These beneficial insects seek out food for themselves and their young. Ladybugs, lacewings, ground beetles, yellow jacket wasps, syrphid (hover) flies, aphid midges and praying mantis fall into this category.

Pollinators

These are beneficial insects that provide us with food since they pollinate flowers in our gardens. 80% of plants need pollinators. They include bees, butterflies, moths, wasps and flies.

Parasitizers

Parasitizers lay their eggs in or on the harmful insects, and when the egg hatches, the larvae feeds on the host. This group can attack their hosts in all stages of life including egg, larvae, nymphs, pupae and adults. Parasitic wasps are the main example of this category.

List of Beneficial Insects that Will Help Control Pest Problems

Lacewings

Green Lacewings are elegant beneficial insects with transparent wings that feed on honeydew, pollen and nectar as adults. Plant cosmos, Angelica, coreopsis, and sweet alyssum to attract them. They are on the beneficial insects list because both larvae and adult feed on pests. Lacewings prey on soft-body garden pests such as aphids, spider mites, leafhoppers, scales, mealybugs, whiteflies, thrips, insect eggs and small caterpillars.

There are two green lacewing species, Chrysoperla carnea and Chrysopa oculata, and one brown one, Hemerobius pacifus. Larvae of both colors are quite similar, the only difference is the that the brown one moves its head from side to side as an adult.

Ladybugs

Ladybugs are super cute with their distinctive red color, although some are orange and yellow. Most species have colored spots or markings on their backs. They are not only a pleasant sight, because of they beauty, but they are also part of our list of beneficial insects. Their diet includes many pests, including mealybugs, aphids, mites, scales, whiteflies, leafhoppers and other insects with soft bodies. Ladybugs love eating aphids, consuming between 50-60 per day, up to 5,000 in a lifetime.

Larvae do not harm plants and they will eat even more bugs, since ladybug larvae can eat up to 40 aphids per hour! Those who want to attract these beneficial insects, should plant yarrow, fennel, dill, Angelica and coreopsis. Having these plants will provide enough food for many generations of ladybugs in your garden. Do not worry about them being attacked by predators, since they secrete an unpleasant odor.

Praying Mantis

Adults are brown, yellow or green in color and range between 5-10 centimeters in length. Praying mantis are fierce predators that will hunt most of the pest that drive you crazy, including flies, beetles, grasshoppers, caterpillars, locusts and months. They grasp prey with they forelegs while they eat them. The downside of having them its that they also eat beneficial insects such as bees and butterflies, and birds like hummingbirds.

Praying mantis even eat their mates and siblings can eat each other when they hatch. Larvae live in the ground where they create galleries and aerate the soil, which helps increase the growth of plants. Attract praying mantis to your garden by planting yarrow, marigolds, fennel, dill and cosmos.

Ground Beetles

This type of beetle is a predator that eats at night while resting during the day. Make sure that you do not kill every type of beetle since some are beneficial, while others such as the Japanese beetles are quite harmful. Adults are black or have a metallic shine in their bodies. There are over 2,500 species of ground beetles.

Both adult and larvae ground beetles can control your problems, since they eat silverfish, slugs, weevils, chirps, caterpillars, root maggots, jassids, aphids, cutworms and nematodes.

Ground beetle larvae develop in the soil, so they are particularly useful. One larvae alone can eat more than 50 caterpillars. While some adult species will climb up a plant and hunt. Plant perennial plants since they leave their larvae in the ground after summer, staying there until spring. You can also have a compost pile (they help eat it) or white clover to attract them.

Soldier Beetles

Another beneficial type of beetle is the soldier beetle that is attracted to plants with compound blossoms. They eat aphids, caterpillars, Mexican bean beetles and Colorado potato beetles. Unfortunately, they also eat harmless and beneficial insects. You can attract soldier beetles by planting hydrangea, marigolds, zinnias, goldenrod and catnip.

Assassin Bugs

These predators have sharp mouthparts to eat various types of insect pests in the garden. Make sure to learn how they look, since they are quite similar to squash bugs as adults. These bugs are quite tricky since they can disguise themselves to capture a meal. They feed on almost everything from beetles, aphids, hornworms to caterpillars. If their favorite food is not available they may eat other beneficial insects or even their own kind. Careful not to touch them since they bite hard.

Damsel Bugs

Damsel bugs are very dull looking insects since they are brown in color. They are similar in appearance to assassin bugs, but smaller. Their front legs are used to grab their preys, such as thrips, leafhoppers, caterpillars, aphids and other soft-bodied insects. Nymphs eat small insects and their eggs. You can get some using a net in an alfalfa field. They are attracted to spearmint, fennel and caraway.

Minute Pirate Bugs

Pirate bugs are quite small, measuring 1/16 inch in size, so you may not even notice you have these beneficial insects in your garden. Adults can eat up to 20 thrips per day and are often used in greenhouses. They also kill caterpillars, mites and aphids. If pests are not available, they will drink plant nectar and juices.

Adults have black bodies with a white pattern on their back. They have short life cycles, so several generations can be produced per growing season. Plant alfalfa, yarrow, fennel, mint, daisies and goldenrods to attract these helpful bugs.

Big-Eyed Bugs

These beneficial insects are easy to spot since they have big eyes, oval bodies and are somewhat flat. They are quite small, just 1/8 inch in length. But don’t be fooled by their size, since both nymphs and adults feed heavily on insect eggs, aphids and mites.

Robber Flies

These bug eating machines are quite evil looking, but they do not attack humans like horseflies. They have extra-long legs which make it very easy for them to eat garden pests. Robber flies are not the best to control pests since they also eat bees, dragonflies and butterflies. Chamomile, mint, daisy and catnip attract them.

Hover Flies

This tiny fly looks similar to a bee but they do not have a stinger. Hover flies are also known as Syrphid. Their larvae look like maggots with no legs or heads. Larvae are wonderful predators, since they suck the juice from their victims which include beetles, caterpillars, scales, thrips and aphids. Adults feed on pollen and nectar, making them one of the best pollinators to have in your garden.

Tachinid Fly

The larvae of the tachinid fly destroys caterpillars and moths from the inside, since they burrow their way in as a parasite. Having tachinid flies means not having to worry about cutworms, which are moth caterpillars that feed on plants bellow the ground. The downside is that they eat butterflies and the caterpillar of endangered monarch butterflies.

Tachinid flies are quite small, so they often go unnoticed. If you want them in your garden, then you should plant sweet clover, cilantro, lemon balm, tansy, parsley, dill and other herbs.

Parasitic Wasps

These wasps are so tiny that you may not even notice they are there. Those that grow tomatoes and have problems with tomato hornworms (and other caterpillars), may notice white cocoons on their backs which are the parasitic Brachonid wasp’s larvae. Do not kill these worms since you would be killing beneficial insects that will turn into more wasps, helping you with your pest problem. Adult females also deposit their eggs on caterpillars, beetle larvae, moths and aphids. Plant dill, parsley, yarrow and wild carrot to attract them to your garden.

Trichogramma wasps looks like a normal housefly, but it is a great parasitizer that lays eggs in over 200 insect pests. These include green stinkbugs, squash bugs, Japanese beetles, Mexican bean beetles, grasshoppers, corn borers and gypsy moth caterpillars. Parasitized aphids, which are black or tan in color, leave exit holes when the adult wasps emerges. Some of these species are commercially available.