Written by Sharon Hanna ©2002
Illustrations by Maria MacRae

For years, well-meaning gardeners routinely and indiscriminately maimed, swatted, sprayed, and stomped every bug they could get their hands on. However, careful observation of nature and the move to organic practices have shown that encouraging "good" bugs, or beneficial insects, is one way to give Mother Nature a hand. She was doing a fine job until many other factors, including pesticide use and overzealous "tidiness", resulted in the loss of normal biodiversity in our gardens.

Just as when you take antibiotics and your doctor recommends eating yogurt to normalize the flora within your body, so the attraction of beneficials back to your garden can restore balance and harmony in your backyard. Think before you squish would make a dandy mantra for the millennium. You may not know the myriad of mysteries that cause creatures to climb the clematis, lurk on the lobelia, or sniff your snapdragons.

It is generally agreed that aphids are "bad", spreading viral diseases and causing growth stunting and general unsightliness to plants in your garden. But, did you know that aphids need to be present on your rose bush for a week or two before the beneficial insects will show up and eat them? Recent studies show that injured plant tissue may be sending out a type of distress signal that attracts the appropriate predators. Be patient — keep your spray trigger finger occupied with turning the pages of the new seed catalogue or knitting.

In general, beneficial insects are attracted to plants from families including Compositae, commonly known as the "daisy" family; mint — all kinds of mints, lemon balm, and more; and Umbelliferae — a large family of plants that form an "umbel", or umbrella-like shape, in the flower head, such as parsley, chervil, fennel, and carrots in their second year. Included in beneficial insect-attracting plants are the Brassica family, a huge family that includes cabbages, cauliflower (all the "stinky when overcooked" vegetables), oriental greens, arugula, broccoli, raab, radish, and more.

All these families produce flowers containing the type of nectar that beneficial insects use as fuel for flight and movement, just as humans use carbohydrates. "Bad" bugs are the protein.

Now, a look at three readily found beneficial insects, and how to attract them to your garden.

Ground Beetles
You undoubtedly know these large, fast moving, shiny metallic-blue-black beetles! Their full title is predacious ground beetles, and I am forever dismayed to see one crushed on the sidewalk, the victim of a shoe whose owner may have had good, but misdirected, intentions. Beetles thrive in deep, loose humusy mulch — the lovely, bouncy kind found in the woods, where leaves, coniferous needles, and other detritus have woven a thick carpet underfoot. There, beetles snooze underneath pieces of rotten logs and stones. Beetles are nocturnal — they enjoy romantic late-evening dinners! They feast ravenously in the dark, and the menu includes cutworms, root maggots, slug eggs, miscellaneous larvae and pupae of undesirables, flea beetles, and leafhoppers.

To attract more beetles, imitate nature. Along a shady edge of your garden, away from foot traffic, dig a ditch three to six inches deep and a foot wide. Plant mint, lemon balm, or even red or white clover, along the inside edges to prevent erosion and to provide low ground cover. Drop shovelfuls of peat moss, leaf mulch, coniferous needles, whatever, here and there along the slopes. Then place a couple of big, flat rocks in the ditch. The beetles will hide under the rocks in the daytime. Beetles are also supposed to be attracted to the nectar of evening primrose — an extremely easy-to-grow native plant which reliably self-sows.

Syrphid Flies
Also known as "hover flies", so named because they can hover in one place, syrphid flies resemble slender black and yellow bees. Syrphids are important pollinators in your garden, but there is another reason to attract them: their larvae prey on many undesirable insects, most especially aphids. Adult syrphids drink the nectar from the flowers, lay eggs, and the larvae gobble up aphids like there's no tomorrow.

With the naked eye it is possible to see eggs on the undersides of leaves near aphid colonies, laid in two symmetrical rows by the female, from 40 to 100 at a time. Once hatched, the larvae decimate aphid families in a hurry. The half-inch larval creature is often mistaken for a nasty "worm" or slug, so if you come across a legless, transparent, greenish-beige creature, who appears to be waving at you with his slightly pointed end - do not kill him! Place gently upon the nearest leaf, and wish him 'bon appetit'!

To attract syrphids, choose plants of the Umbelliferae family, such as fennel, dill, caraway, parsley, coriander, yarrow, or carrots allowed to overwinter, which produce the symmetrical seed-heads favoured by beneficials.

Buckwheat, usually planted as a cover crop, can be sporadically seeded anywhere in the garden. Not only does it enrich the soil when turned in, but, according to a fairly recent Oregon State University study, the flowers are particularly attractive to syrphids. (Some people even consume buckwheat "greens" as food - this may be worth further investigation…) Other favourite flowers of syrphids are cornflowers (bachelor buttons), marigolds, chamomile, Coreopsis, and feverfew.

Lady Beetles
Also known as "ladybugs", these fairy-tale creatures feed heavily on aphids. If you think about purchasing them, remember…in most cases, the ladybugs go into dormancy or diapause when packaged, and when set free their natural instinct is to fly away. Don't waste your money! Instead, attract ladybugs by your choice of plant materials. Become familiar with the ladybug in the larval stage. It looks a bit evil, like an elongated grey-black dragon with many little legs, and orange-red markings. The larvae fix themselves onto leaves, trees, or wood surfaces then pupate for about a week, emerging as the familiar round ladybug of our childhood.

All stages of ladybugs from larva to adult feed on aphids. Ladybugs are attracted to Cosmos, Solidago (goldenrod), Coreopsis, fennel, yarrow, and other Umbelliferae. All are easily grown from seed. Lady beetles and other beneficials, including the spider (yes, they are beneficial), like to lay their eggs amongst the long grass; so try to leave a 2-foot swath un-mowed if you can. When harangued by members of your family, tell them you saw it in the latest hoity-toity garden book — call it 'lawn art asymmetry'.

It is always good manners for you, the host, to provide your insect guests with a drink to wash down the aphids or other menu items. This can be achieved easily by placing a plastic tray or any kind of pan in your garden and adding some rocks for the beneficials to stand on as they drink. Keep the pan water refreshed as needed.

And, be sure to tell your family and friends to think before they squish.

 

Sharon Hanna is a writer, master gardener, vegetable seed specialist and garden communicator living in Vancouver, B. C. She works in an old-fashioned perennial nursery seasonally, and propagates plants in every possible way. Sharon's special interest is nurturing and attracting beneficial insects.