Preemptive Planning: Plants To Trump Pests
In My Garden Blog:
April 5, 2012
By Charlotte Kidd,
Be gone slugs, Mexican bean beetles, squash beetles, and cabbage loopers! Last summer they were the peskiest pests in my vegetable garden. What can I do now to preemptively reduce their presence and damage this summer?
Hmmm. How about growing plants that attract beneficial insects (predators) who feed on these pests? And creating habitat to encourage them to come, stay, reproduce, devour pests? Diverse plant material is essential to a healthy, well-balanced landscape. The same principle applies to a thriving, sustainable vegetable garden.
Let’s begin by matching my pesky garden pests with the beneficial insects who hunt them. They are the basic good predators — ladybird beetle (lady bugs) adults and black-orange, spiny larvae; tiny parasitic wasps; spined soldier beetles; green lacewing larvae; toads; and birds.
Which flowers and herbs do adult and young beneficials feed on? What natural materials provide shelter? Nectar and pollen rich native plants and moist, protective crannies tend to fill this niche. (Which plants and techniques have you found to be helpful?)
Fennel with its umbel flowers and fine foliage tops the list as a nectar and pollen host for a wide variety of beneficial insects. Other umbel favorites for parasitic wasps and ladybird beetles include Queen Anne’s lace, parsley, coriander, dill, yarrow, tansy, angelica, anise, caraway, and mustard.
The aster family of composite flowers is a prime nectar source for ladybird beetles, small parasitic wasps, lacewing larvae, Syrphid flies, and hover flies. Aster, daisy, bachelor’s buttons, goldenrod, black-eyed Susan, coneflower, chamomile, Coreopsis, ironweed, sunflower, thistle. These composites have a center disk of small and short symmetrical flowers accessible to small insects.
Which Beneficials Eat Which Pests?
Green lacewing larvae eat the eggs of caterpillars, mites, thrips, aphids, mealybugs, scale, and whiteflies. Adults feed on nectar and pollen.
Toads, lizards, turtles, birds (robins, starlings, wrens, warblers, chickadees, purple finches, blackbirds, blue jays), grass and garter snakes, salamanders snack on slugs.
The spined soldier bug is a native beneficial predator, not to be confused with the destructive, invasive brown-marmorated stink bug. The eats larvae of the Mexican bean beetle, cabbage looper, imported cabbageworm and 80-plus other insect species. Though the spined soldier bug seems an impressive, effective, good predator for nearly all my garden pests, I only found one reference to its preferred habitat — a permanent perennial bed.
The beneficial ladybird beetle — seven-spot, 12-spotted, and convergent — adults and (wee, alligator-look alike) larvae feast on caterpillars, aphids, scale, mites, and white flies.
Location, Location, Location
Creating wildlife-friendly habitat invites good predators (and prey). A toad may move from a nearby pond to my (or your) garden enhanced with a small pile of stones, bark, and leaves plus a sheltered, sunken dish of water. An open birdbath encourages birds. Don’t put it near the toad abode; the birds will have an easy meal. A natural spot with brambles, nettles, and wildflowers offers diverse shelter and food to insects, birds, native bees, butterflies, and honeybees. So does a more designed, complex habitat of groundcover, trees, and shrubs.
Here’s to fewer pests in the garden and more squash, cucumbers, and beans on our plates this summer!
Thanks to these resources: Rodale’s Flower Garden Problem Solver, Timber Press’s Bringing Nature Home, Rodale’s The Organic Gardener’s Handbook of Natural Insect and Disease Control and Audubon at Home.