Your garden's most prolific pest, the aphid, is also one of the easiest to deal with. Usually all you need is a bit of patience or, lacking that, a spray nozzle on your hose.
Dave Shetlar, Ohio State University
Party crashers: Aphids love new growth on trees… on nearly every plant, actually.
Tiny and pear-shaped, aphids are easy to miss. That is, until suddenly they're clumped by the hundreds or thousands on your flowers, veggies, or trees' fresh new growth. Aphids come in designer colors pastel pink, gray, yellow, green, beige, lavender, dusty black, or red. Some even have a fluffy white coating. Aphids make their living by sucking sap from a plant's leaves and stems.
Dave Shetlar, Ohio State University
Making babies: That big aphid on the right is giving birth. Her baby will get right to work sipping up sap, and will give birth herself in about a week.
Safe sex: How did the aphids get there so fast? Most of the time aphids don't bother to lay eggs, but just pop out live babies one after the next babies that are born already pregnant. Talk about fast: aphids rarely take time out for sex. They don't need to, since most aphids are females and clones of their moms. When conditions are right, aphid numbers can double every couple of days.
How to cope?
The "do-nothing" cure: If aphids get the upper hand, leaves will fade, curl up, wilt, and turn yellow. Black sooty mold can grow on the sticky "honeydew" that aphids secrete. But this rarely happens. About five days after aphid populations explode, the good bugs kick in. These natural enemies include lady beetles, tiny parasitic wasps and midges, damsel bugs, and more. So usually the cure is ... do nothing!
They're on your side
Keith Waldron, NYS IPM Program
Tiny mummies: You'll know that parasitic wasps are on the job if you see these aphid mummies.
The water cure: Too antsy to wait for natural enemies? Hit 'em with the hose. Use your spray nozzle to blast aphids with water three mornings running and you'll kill most of them. If you must use a pesticide, an insecticidal soap solution (easier on your plants than dish soap) is among the least-toxic choices. Be sure to saturate the undersides of leaves. But pesticides kill natural enemies too, and after a few days the aphids bounce right back. If you do decide to spray with a pesticide, always read and heed the label.
Be on the lookout: Scouting for pests is the best way to keep problem pests from getting out of hand. You've probably got "indicator plants" in your garden. These are plants that are especially attractive to aphids. So keep an eye on your nasturtiums, calendula, asters, mums, cosmos, hollyhocks, larkspur, tuberous begonias, verbena, dahlias, and zinnias. In the vegetable garden, watch your spinach, snap beans, kale, squash, and melons. If you see aphids on any of these plants, start scouting the entire garden.
Prevention is the best cure: Fertilizer can make plants grow fast, yes, but it's that fresh new growth that's so attractive to aphids. Save the hassle by fertilizing lightly, if at all. Avoid "quick-release" nitrogen fertilizers. Instead, use compost or "slow-release" natural fertilizers. And plant lots of different herbs and flowers to provide homes and nourishment for natural enemies.
For more information on IPM, click here!
Mary Woodsen is a science writer with the New York State Integrated Pest Management Program at Cornell University. Bugs and bats; dandelions and diseases like dollar spot; farming, gardening, houseplants she writes about them all.