Not All Bugs are Bad Bugs

Beneficial insects are a natural control against garden pests.

Your gardens can host more beneficial insects and animals than pests when you plan for them. While gardeners can buy and release beneficials into gardens, you're better off enticing them to come and stay. Most beneficials won't if they can't find the food or shelter they need. Keep soil healthy to encourage beneficial organisms. Healthy soil contains fungi and bacteria that fight soil-borne organisms that can cause plant diseases. Adding organic material such as compost, manure, leaves or grass clippings to your soil encourages helpful soil organisms.

Below is the damage that insect pests do, the various predators and parasites that prey on the pests, and some of the ways to encourage them to come and stay in your gardens.

• Aphids and mealybugs remove the sap from plants causing curling, yellowing and distortion of leaves while stunting the growth of shoots. They produce a sticky exudate known as honeydew, which attracts ants. The ants carry the pests to uninfested plants, protecting and "milking" them for the honeydew, which the ants highly value.


• Armyworms attack foliage and fruit, creating circular or irregular holes.


• The larvae of the cabbage loopers feed on the underside of lower leaves, skeletonizing them.


• Cutworms feed on leaves and crowns and tend to cut off plants near the soil surface.


• The coddling moth larvae penetrate fruit, boring into the core and leaving brown-coloured holes in the fruit.


• Earwigs feed on leaves and fruit, leaving small deep holes.


• Hornworms feed on blossoms, leaves and fruit, defoliating plants and scarring the fruit.


• Leafminers are aptly named as the larvae mine between leaf surfaces, creating winding tunnels, which widen as the larvae grow.


• Root maggots feed on succulent roots, causing plants to wilt and become stunted.


• Scale insects decrease the vitality of their host by sucking sap from the leaves, twigs, branches and trunk.


• Slugs and snails chew large irregular holes in leaves.


• Spider mites cause damage by sucking cell contents from leaves.


• Tent caterpillars build large silken tents over leaves, which they skeletonize while feeding on them.


• Thrips cause tiny scars, called stippling, on leaves or fruit and can stunt growth.


• Whiteflies feed on leaf tissue, removing plant sap and stunting plant growth.

Beneficial Insects and their Prey

• Ground beetles love to eat cutworms, root maggots, slugs and snails.


• Ladybeetles, also called ladybugs, dine on aphids, mealybugs, scale insects, spider mites and whiteflies.


• Lacewings are good for controlling aphids, spider mites and whiteflies.


• Parasitic wasps help you get rid of aphids, cabbage loopers, hornworms and whiteflies.


• Syrphid fly larvae (adults are called hover flies) prey on aphids and mealybugs.


• The tachnid fly munches cabbage loopers, coddling moths, cutworms and tent caterpillars.

Nectar Lures Insects

There are several flowers and herbs (herbs should be allowed to flower) that will lure beneficial insects. Plants such as aster, camomile, marigold, oregano, sage, sunflower, thyme, yarrow and zinnias will attract hover flies, lacewings, ladybeetles and parasitic wasps.

Give Beneficials a Drink

Fill a shallow dish with small stones and add enough water to create shallow pools among the stones. Since many beneficial insects are tiny and can drown easily, be sure your bath has dry areas where they can land.

Beneficials aren't Just Insects

Provide food and shelter to attract insect-eating birds. Birds will harvest thousands of insects during the weeks when they raise their young. Baby birds can't digest seeds and are fed fresh insects. Putting up birdhouses, planting flowers whose seeds birds will eat, planting trees and shrubs for shelter and with berries for food will attract birds.

Put an overturned flowerpot with a hole broken in the side, along with a half-buried water dish in your garden to shelter and attract toads. Toads can eat 24,000 insects in one active season. They will devour ants, aphids, caterpillars, cutworms, grasshoppers, slugs and squash bugs. Turning the porch light on will also attract toads at night and they will stay as long as they have a hiding spot or two.

In British Columbia the frog and toad population is unfortunately on the decline. One problem is the major pollution from logging and building flowing into the water ways and diminishing food sources. Another factor is the increase in the population of bull frogs. These giants, originally brought to BC as pets, have grown in population and are eating the native amphibians.

Bats and Snakes

There are many myths surrounding bats. These mammals do not bother humans unless they are cornered or provoked. They venture out in the early evening to search for insects. A single bat can eat over 1,000 mosquitoes a night. Night-flying insect bats are an excellent beneficial.

And don't chase away the garter snakes. Snakes prey on rodents and eat bugs and beetles. Allowing them to hunt in and around your flower beds will curb the population of voles, mice and rabbits as well as pest insects.