Sometimes people call my office and ask what to do about all the bugs. Since 99.9% of insects are either beneficial or harmless, the usual answer will be nothing.
Many insects are actually beneficial as insect predators, parasitoids, pollinators, weed killers, and even decomposers.
One of the largest orders of insects is the order Coleoptera or beetles. You can probably think of a few beetles (including weevils) that are pests: alfalfa weevil, carpet beetle, root weevil, flathead borer, emerald ash borer, hollyhock weevil, etc.
There are many, many more that are beneficial. Here are a few :
Ladybugs (ladybugs, ladybugs) are a group of predatory beetles. Both adults and larvae are predators of aphids, mites, leafhoppers, mealybugs, thrips and whiteflies. There are a few species in the lady beetle family that feed on desirable plants, such as the Mexican bean beetle and squash beetle, but I haven’t seen them in eastern Idaho yet.
Adults and larvae are predatory. Adult beetles forage crops and feed on soft-bodied insects, caterpillars, Lygus bug nymphs, and other small insects. The larvae are active in the soil as predators of soil-dwelling insects and grasshopper eggs.
Adults and larvae are predatory. Almost all checkered beetles are predators of smaller insects. Some feed on grasshopper egg pods. Others feed on the larvae of tree-boring insects. Some feed on bee larvae.
There are many species of ground beetles that are predatory both as larvae and as adults. They can consume their body weight in aphids, beetles, caterpillars and grasshoppers daily.
The rove beetles are more like earwigs without the claws. When disturbed, they often hold their abdomen up and look a bit like a small scorpion. Both adults and larvae of rove beetles are very good predators of soil pests such as fungus gnats, slugs, snails and soil stages of thrips.
Soldier beetles feed both at ground level and in canopies. Both larvae and adults prey on aphids, slugs, snails, insect eggs, scale insects, caterpillars, root maggot larvae and other soft-bodied insects.
Tiger beetles are very fast hunters and in the open ground. Larvae and adults are predatory. They feed on a wide variety of arachnids and insects such as ants, beetles, caterpillars, flies and grasshopper nymphs.
Adults and larvae feed exclusively on salt cedar or tamarisk.
The adult females chew the young flower heads and lay their eggs. After hatching, the larvae feed on the seeds of most biennial thistles. Although they prefer musk thistle, they also feed on native biennial thistles, so their use is not encouraged.
Turtle beetles are phytophagous beetles. A few species are specific to field bindweed and musk thistle.
Conserve and Encourage Beneficial Beetles