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Insects for Garden Pest Control

Or….Good Bugs that take care of Bad Bugs…

Fewer things are more frustrating for gardeners than strolling through the yard, admiring years of hard work, only to discover prized roses devoured by aphids and foliage eaten, chewed and destroyed by mealybugs or mites. Fortunately, not all insects damage plants and turn the gardening into a feasting ground. Lucky for us, many insects feast on those same insects that cause the damage. Encourage beneficial insects into the garden with the right plant, and a clean environment and let them take care of removing the unwelcome ones.

Here’s a few of the good ones:

Lady Beetles:

Also known as lady bugs, lady beetles eat aphids, whiteflies and other soft-bodied insects that are often found destroying bright blooms and plant foliage. Round to oval in shape and usually spotted, lady beetles consume up to 50 aphids per day once weather conditions warm up. The young larvae will eat up to 400 per day before transforming to adult insect. Dormant lady beetles are available for purchase at some garden supply centers and when released into the garden will start to do their magic. 


Also called praying mantis, this odd-looking insect will devour any garden pest. Large front legs grasp at prey, and their large triangular heads allow them to observe and search for pests at any angle with minimal effort. Eggs overwinter in pods attached to solid surfaces, and young mantids hatch in early spring, quickly beginning their search for food. Available from many garden centres, dormant egg pouches will give the garden a good head start in the fight against bad bugs in early spring as the mantids burst out.   


One of the most effective beneficial insects, lacewings will take care of caterpillars, aphids, leafhoppers, whiteflies, mealybugs and insect eggs. The larvae of lacewings look like tiny quarter-inch alligators and the adult develops greenish-blue lacy wings that carry it from plant to plant in search of prey. Plenty of flowers will keep lacewing working in the garden, as the nectar provides the lacewing with the needed energy for hunting.

Beneficial Nematodes:

Beneficial nematodes are microscopic worms that work under the soil surface, removing grubs and larvae that grow into plant-damaging flying insects like Japanese beetles. Different nematodes attack different pests, so ensure you have the right predator for the job before applying them to the lawn area. Nematodes are used for insects that spend part of their life cycle underground, where the nematodes wait for the pest to move through the soil, and then take action and destroy it.

Parasitic Wasps:

Parasitic wasps grow to varying sizes and prey on a number of caterpillars including cabbageworm, tent caterpillars and tomato fruitworm. The trichogramma, one parasitic wasp the size of a speck of dust, lays up to 300 eggs inside pest larvae, destroying the developing insects. Larger wasps lay their eggs on the caterpillar and as the eggs hatch, they kill the insect. Parasitic wasps are also a good defence against aphids.

Other Considerations:

Plant a variety of flowers that attract beneficial insects, to keep them working in the garden all season long. Keep the garden clean to eliminate spots for the bad bugs to hide, and as plants fade or go dormant at the end of the season, remove any debris from the garden. Remove or prune damaged or weak plants during the season because these can become targets and home for garden pests

Photo by Michael Willinger on

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It’s Japanese Beetle Season!


Nothing is quite as frustrating for gardeners as strolling outside, admiring their hours of hard work and discovering plant damage. It becomes even more annoying to see the foliage and at times, flowers of your prized roses, dinner plate hibiscus, morning glory vines, or lush pole bean plants riddled with holes while the culprit brazenly sits upon yet another damaged leaf, staring back as if daring you to flick it away, in hopes of landing on its next unsuspecting victim.

Discovered in North America in the early 1900s, the Japanese beetle is one of the most destructive garden pests around today. Measuring about a ½ inch long, with an attractive shiny metallic-green body and copper coloured wings, the list of plants this beetle avoids is short, tending toward trees and most garden selections including fruit, flowers, vegetable plants and foliage. They are all at risk of becoming part of the beetle’s summer diet.

Japanese Beetle Larvae

These voracious eaters begin their garden buffet at an early age. Unlike moles or other underground garden rodents that clean off grass roots and cause temporary disturbances in the lawn, the Japanese beetle larvae devour roots, destroying lawns and killing young vegetable seedlings. While it prefers well kept and fertile turf areas, the Japanese beetle larvae is not terribly picky and will destroy vegetation in just about any type of soil conditions. The larvae (grubs) begin as eggs planted shortly after the adults emerge from the ground in spring and each female beetle lays up to sixty eggs per season that develop into full-grown grubs by the end of summer. The grubs burrow deep into the soil as the temperatures drop from fall to winter, and head back to the soil surface in the spring as the warmer weather returns, where they feast on plant roots for up to six weeks before becoming adults and leaving their childhood home in search of foliage and flowers.

Adult Japanese Beetles

A single Japanese beetle wandering through the foliage will do little harm, but it is rare to find this pest travelling solo. Usually feeding in groups, the adult beetles chew through plant tissue beginning in late June, leaving behind an irregular, lacy-looking version of what the foliage or flower once was. Typically starting at the top of their chosen plant, the beetles eat their way down the vegetation and when done, fly off to their next meal. During their short seven-week life span, Japanese beetles will feed fervently on hot summer days, focusing on plants grown in full sun, eating less on days with cloud cover or wind, and staying away when rain is falling.  

Control Options

Controlling Japanese beetles is challenging. Dealing with one life stage does not always ensure elimination of the next and with adult beetles flying from location to location, numerous families of beetles may visit over the course of the season. Beneficial nematodes attack grubs and are best applied as the young return to the soil surface. Nematodes need moist soil conditions and soil temperatures of at least 68 degrees Fahrenheit to be effective. Adult beetles can be hand-picked from plants or shaken from their perches into soapy water early in the morning, while still sleepy. Removing the pests from the plants reduces the number of beetles that assemble; they prefer to gather in numbers, and feeding beetles attract further pests to the same plant. Chemical controls are available for Japanese beetles, but local laws may or may not permit their use. Japanese beetle traps work well, using pheromones and food scents to lure the insect and can capture hundreds of adult beetles over the summer. Placement of the traps is tricky though as plants on the trap route may fall victim to the beetle before making its way into its final destination. And if your neighbours aren’t using them, you’ll get all of theirs. 

Over the past couple of years, I’ve stopped using the traps and have seen a huge reduction of these beetles in the yard. Sure, I still have some, but removing the traps seems to have stopped them from arriving in hoards and staying. It’s a personal choice, but I’d say, worth a try.