Beneficial Insects
Know a Friend from a Foe
Learn what is and is not a pest, as well as what’s doing the damage. Is it a fungus or an insect (damage caused by either can often be confused)? Or is it environmental? Many common insects neither help nor harm plants, and many others are helpful predators or parasites. For example, you've probably heard that ladybug larvae look menacing and bad but in fact they are voracious consumers of aphids, a common garden 'pest'. Ground beetles also don’t look too friendly, but they love to eat slug eggs (great news for any gardener!). Even if you identify an insect as a plant eater, consider that the predators and parasites in your garden would probably like to eat it much more than you would like to spray it. Also ask yourself, "Will this one pest will cause damage that will adversely affect the whole plant?" If not, let it go and spend your time on more fruitful endeavors, such as producing an environment that will result in healthy plants and lots of places for predators to thrive.
Common Beneficial Insects
Ladybugs
These common insects consume aphids, mites, whiteflies and scale.
They can be attracted to your garden by planting members of the daisy family
(Compositae), tansy or yarrow. Ladybugs can be found in a variety of colours
– the black ones are especially special in the Lower Mainland, as they
are native to the area. Even more important is the larval stage of the ladybug
– they have six legs and are shaped like alligators! They are voracious
eaters of pest insects, especially aphids. Unfortunately, die before they can
do their good work because many gardeners think they are harmful. (Click
here
for some photos to help you identify ladybugs and their larvae)
Lacewings
Lacewings are avid consumers of aphids, and their larva eat aphids
and other varieties of insect pests including caterpillars. They are attracted
to "composite" flowers, such as yarrow, goldenrod, black-eyed susan's
and asters. (Click
here for some photos to help you identify lacewings and
their larvae)
Hover-flies
Y ou most often see these beneficials ‘hovering’ above flowers. Hover-flies are also avid consumers of aphids and the hover-fly larva, which looks like a tiny slug, is one of the best predators against aphids and other insect pests. Like the lacewings, the hoverfly is attracted to "composite" flowers, such as yarrow, goldenrod, black-eyed susan's and asters. Seeds for these flowers are available online, or at most garden centers.
Predaceous Ground Beetles
This large, glossy dark brown or black beetle with grooves down its back is a predator and will eat many insects. It is especially fond of slug eggs and root maggots. These beneficials thrive very well in landscapes where there are a lot of perennials and undisturbed areas (they like to hide in mulch).
Syrphid Flies (Several species, Family Syrphidae)
Sometimes called flower flies, this is one of the most beneficial
groups of insects in your yard and garden. Adult stages of these insects are
usually colored bright orange or yellow and black and resemble bees and wasps
– but they do not sting! They are often found near flowers, where they
feed on pollen and nectar. Their larva are slug-like, are legless and are piggies
when it comes to eating aphids! (Click
here for some photos to help you identify syrphid flies
and their larvae).
Brachonids,Chalcids and Ichneumon Wasps
These small beneficial insects destroy leaf-eating caterpillars. The larvae are parasitic and prey on soft-bodies pests. You can attract them to your garden by planting carrots, celery, parsley, caraway and Queen Anne's lace, all members of the Umbelliferae family. These plants are easy to grow, and some should be left to flower. It's the flower that attracts the insects.
Nematodes
Nematodes are effective against cutworms, a common pest which destroys sprouts before they can grow into seedlings. Nematodes are also effective against beetles and root weevil larvae. Nematode eggs are microscopic and come in a small sponge a million at a time. These are mixed with water and applied to the soil, where they hatch and do their work (link to sidebar below for more info).
Yellowjackets (Wasps)
Yellowjackets are picnic pests because they are attracted to the protein in chicken, hot dogs, and other barbecue fare. When they aren't at your barbecue, however, they are busy collecting insects to take back to the hive and feed the growing larvae. They are efficient predators, and do the gardener much more good than harm.
Spiders
Spiders are probably the best insect control in your yard. They eat a wide variety of insects and are very common.
Earwigs
Earwigs are omnivores and are great predators. They are beneficial in a compost bin and are encouraged in the Okanagan where they are great for pear trees.
How You Can Help
You can provide habitat for beneficials by companion and interplanting (link this to the explanations in the ornamental section). Use a mixture ofvegetables, flowers, and herbs with wild patches scattered throughout. Keep in mind it is often the larva of the beneficial insect that eats the pest insects. You can attract the adult of these beneficials by planting a range of pollen-rich flowers, because the adults feed on the nectar and pollen from these flowers. A couple of suggestions are sunflowers, dill, sweet alyssum, daisies, yarrow, and goldenrod. Many of the seeds for these flowers and herbs and the ones mentioned above are available online, or at most garden centers.