Plants That Attract Pest Controlling Insects

Plant plenty of herbs such as caraway, coriander, crimson dwarf thyme, dill, fennel, lemon balm, parsley, pennyroyal, spearmint and wild bergamot and you’ll attract predators and parasitoids of many of the most aggravating garden pests.

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Challenged by a ban on ‘chemical’ pesticide use for many home gardeners and growing realization that ‘natural’ or ‘organic’ insecticides can be equally deadly for friend and foe alike, some gardeners are turning to plants that attract pest controlling insects. There are an astounding number of these too often overlooked silent assistants in the long-fought battle of the bug. Unfortunately the use of any pesticide – natural or unnatural – decimates our collective colleagues. Spider mites, for example, went virtually unnoticed until the 1950s and introduction of organophosphates. The mites rapidly built up resistance but not so their natural predators: bigeyed bugs, minute pirate bugs, sixspotted thrips, Stethorus picipes (spider mite destroyer lady beetle), and Feltiella spp. (predatory cecidomyiid fly larvae). And we all know the result. There is a border full of perennial flowers that will also attract our predacious buddies from early spring to late fall. The list is vast but those more easily found even in chain store garden centres include Common Yarrow (Achillea millifolium) and Fern-leaf Yarrow (A. filipendula), groundcover Carpet Bugleweed (Ajuga reptans), Basket of Gold (Aurinia saxitalis) as an early attractant, Golden Marguerite (Anthemis tinctoria), Butterfly Weed (Asclepias tuberosa), English Lavender (Lavendula angustifolia), Rocky Mt. Penstemon (P. structus), Sulfur Cinquefoil (Potentilla recta ‘warrenii’), Alpine Cinquefoil (Potentilla villosa), Black-eyed Susan (Rudbeckia fulgida), Stonecrops (Sedum spurium), Tansy (Tanacetum vulgare), and Spike Speedwell (Veronica spicata).

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The nectar and pollen of these blooms will feed our friends while their larvae go to work reducing pestiferous hordes. For in a large part it is the larvae of predacious and parasitic insects that feast on our foes. True, adults of the much cited ladybeetles eat aphids but their young are positively voracious. Other adult Coleopterans are the nocturnal hunting ground beetles (Carabidae), soldier beetles (Cantharidae) that consume aphids, and rove beetles (Staphylindae) that eat both mites and snails Lack even space for a perennial border? Not to despair – a few containerized annual flowers will also act as attractants. Centre a large planter with Cosmos ‘White Sensation’ (C. bipinnatus), surround this with Statice (Limonium latifolium), then these with Marigold ‘Lemon Gem (Tagetes tenuifolia) and edge with beautiful blue Edging Lobelia (L. erinus), scented Sweet White Alyssum (Lobularia maritima) and perhaps Trailing Zinnia ‘Lilliput’ (Z. elegans). So why not purchase predacious insects from commercial online suppliers? Despite the hype it isn’t that simple. It may occupy much space in the popular press but many scientists are dead set against the practice. On an industrial agricultural scale this can be effective. In the home garden, however, it rarely is. Worse yet, the predators may become invasive invaders themselves, such as the now-notorious oriental ladybeetle and the Chinese praying mantis. The bottom line is that we need to become more familiar with our friends. A pocket hand lens should accompany gardeners wherever they go. One used by philatelists with two magnifications and a built in light can be especially useful. Home library insect identification publications are thin on the bookshelf and even thinner in practicality. A Field Guide to the Insects of America North of Mexico by Donald L. Borror and Richard E. White in the Peterson Field Guide Series can be recommended with the proviso that with almost 100,000 known species in this area a complete written description is impossible, let alone illustrated. Ancient advice from across the Atlantic suggested if it moves slowly, step on it but if it is fast moving, leave it – it is probably a predator. Today, we can simply say don’t spray. Plan now to plant a garden full of flowers this spring that advertise a welcome for our predacious guests. Garden Foes and Friends: Recommended by the University of California as the natural enemies of invertebrates and use in biological control: Aphids soldier beetles, syryphid fly larvae Caterpillars predaceous bugs and wasps, spiders Elm Leaf Beetle parasitic wasps, Erynniopsis antennata (parasitic fly) Glassy-Winged assassin bugs, spiders, egg parasitic wasps (Gonatocerus spp.) Sharpshooter Lace Bugs assassin bugs, pirate bugs, spiders Mealybugs mealy bug destroyer lady beetle Psyllids pirate bugs Scales parasitic wasps: Aphytis, Coccophagus, Encasia, Metaphycus spp. Slugs, Snails predaceous ground beetles, predatory snail (Rumina decollata) Spider Mites bigeyed bugs, minute pirate bugs, sixspotted thrips, Stethoruspicipes (spider mite destroyer lady beetle), Feltiella species (predatory cecidomyiid fly larvae) Thrips minute pirate bugs, predatory thrips Whiteflies bigeyed bugs, minute pirate bugs, spiders, parasitic wasps (Calesencarsia, Eretmocerus spp.)

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