This article appeared in the June/July 2009 issue of GRID, Philadelphia’s new magazine about urban sustainability.
When most people think of insects, they think of mosquitoes that bite, bees that sting, and a host of annoying bugs that munch leaves and plants. Truth is, there are vastly more beneficial insects than pests in the garden. In fact, we’d all quickly starve without the pollination they provide for nearly all of our food crops. Insects are indeed essential to a healthy garden ecology.
Problems with pest insects generally result from a lack of ecological balance. A healthy garden may have some aphids and other pests, but it will also have a wide variety of predatory and parasitic insects to keep their populations under control. Attracting these beneficial insects to your garden is the easiest and safest way to keep pest damage to a minimum.
So who are some of these garden allies?
LACEWINGS: One of the best predatory insects, these little guys flutter around the garden on delicate green wings at dusk. Their larvae are known as ‘aphid lions’, but lacewings also attack thrips, caterpillars, mites, and more! COMPANION PLANTS: Dill, goldenrod, dandelions.
LADYBUGS: There’s a reason these spotted beetles are considered lucky, as their presence helps protect your garden from bothersome pests. Their larvae look like tiny alligators and voraciously consume aphids, mealy bugs, scales, and spider mites. COMPANION PLANTS: Yarrow, sunflowers, mint.
BRACONID WASPS: These tiny wasps don’t sting, but gruesomely parasitize everything from gypsy moths to cabbageworms to cornborers. After laying eggs inside their prey, their young eat their victims alive from the inside out. How’s that for revenge against your enemies? COMPANION PLANTS: Fennel, coriander, queen anne’s lace.
MASON BEES: Just one of many types of native bees that are essential for pollination of fruits, nuts, and vegetables. Unlike honey bees, they are solitary and don’t form hives- they also don’t sting! Making a mason bee home is a fun project for kids and is great for the garden. COMPANION PLANTS: Clover, hyssop, beebalm.
DADDY LONG LEGS: Eight legs good! Like the spiders they are closely related to, these useful fellows feed almost exclusively on all kinds of insects. COMPANION PLANTS: Comfrey, yarrow, nettle.
How do I attract and keep them in my garden?
1. Avoid spraying chemicals. Insecticides are generally indiscriminate, killing good and bad bugs alike. In the long run this will only make your problems worse. The pests will quickly return and, in the absence of predators, their populations will explode and devastate your garden. By the time your natural insect allies return, the damage will be done.
2. Feed your insect friends with beautiful flowers. Besides eating pest insects, many beneficials also feed on pollen at different stages of their life cycle. Attract them by planting a wide variety of annual and perennial flowers. Keep them in the garden by making sure you have something blooming in all seasons. Plants with clusters of tiny flowers (the umbel and aster families in particular) are often the best for bringing in beneficials.
3. Provide a home for your new garden allies. Ideally you want them to stay in your garden year round as a permanent garrison of pest protection. Dense vegetation, fallen leaves, mulch, and rock piles all provide good shelter for beneficials to live and reproduce. If possible, leave your end-of-season garden clean up until Spring to allow your insect friends to overwinter. Pre-industrial farms always had hedgerows, wild spaces in between fields that provided habitat for a balanced ecology. You can apply the same principle in any sized yard or garden. Consider leaving one corner of a larger property to grow wild at nature’s whim. In smaller gardens, the approach can be as simple as interplanting some flowers with your veggies.
4. Create a watering hole. Although many beneficials meet their moisture needs from drinking nectar, others need a water source to stay hydrated or to reproduce. This can be accomplished with something as simple as a birdbath or as ambitious as a greywater processing pond.
Learn more: The Organic Gardener’s Handbook of Natural Insect and Disease Control, Ellis & Bradley; Gaia’s Garden, Toby Hemenway.