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Beneficial Insects and How To Attract Them
by Sharon Hanna - New Writer!
by Sharon Hanna

Sharon Hanna is a seed specialist, writer of seed catalogues and non-fiction/fiction, master gardener and teacher, who also works in a nursery doing plant propagation. Fundamentally she considers herself to be a "creative urban agriculturist" with a strong inclination toward re-familiarizing humans with their humanity via gardening. Besides food gardening, Sharon has a special penchant for understanding and attracting beneficial insects.

She lives in Vancouver, B.C. and is the garden co-ordinator for KidSafe

February 24, 2002

For years, well-meaning gardeners routinely and indiscriminately maimed, swatted, sprayed and stomped upon 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, however many factors including pesticide use and overzealous ‘tidiness’ has resulted in loss of normal biodiversity in our gardens.
Just as when you may have taken 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 back yard. And think before you squish would make a dandy mantra for the millennium. You may not know the myriad of mysteries which are causing any creature to climb the clematis, lurk on the lobelia, or sniff your snapdragons. 
It is generally agreed that aphids are “bad”, spreading viral diseases and generally 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 which may be attracting appropriate predators. Be patient, and 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; Umbelliferae - a large family including plants which form an “umbel”, or umbrella-like shape in the flower head: parsley, chervil, fennel, carrots in their second year. Included in beneficial insect-attracting plants are the Brassica family, a huge family which includes cabbages, cauliflower (all the “stinky when overcooked” vegetables) oriental greens, arugula, broccoli raab, radish and more. 
All these families produce flowers which contain the type of nectar which beneficial insects use as fuel for flight and movement, just as humans use carbohydrates. “Bad” bugs are the protein course. 
Now, a look at three of the more commonly found beneficials, and how to lure them to your garden:


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. You should be, too, for beetles are important to the balance of your garden. They 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. By day, the beetles snooze away underneath pieces of rotten logs and stones. Beetles are nocturnal, and enjoy romantic late-evening dinners! They feast ravenously in the dark, and the menu includes cutworms, root maggots, and slug eggs, miscellaneous larvae and pupae of undesirables, flea beetles, and leaf hoppers.
To attract more of these lovely creatures, imitate nature. Along a shady edge, away from foot traffic, dig a ditch three to six inches deep, and a foot wide. Plant mint, or 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 supposed to be attracted to the nectar of evening primrose - an extremely easy-to-grow native plant which reliably self-sows.

Syrphid Flies

AKA “hover flies”, so named because they can hover in one place, 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, and 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 ½” larval creature is often mistaken for a nasty “worm” or slug, so if you come across a legless, see-through 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: fennel, dill, caraway, parsley, coriander, yarrow, or allow carrots to winter over. All produce the symmetrical seed-heads which are 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 maximally attractive to syrphids. (Some people even consume buckwheat “greens” as food - this may be worth further investigation…) Other favourite flowers: 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 they are set free their natural instinct is to fly away. Don’t waste your money! Instead, attract ladybugs by your choices 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 to 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, to Solidago (goldenrod - achoo!), Coreopsis, fennel, yarrow and other Umbelliferae. All are easily grown from seed. Lady beetles and other beneficials including the spider (yes, he is 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 assymetry’. 
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 simply: place a plastic tray or any kind of pan in your garden, and put some rocks in the pan 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, 2002 

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