How to Identify Aphids
Often the first sign of an aphid infestation is not the visible presence of the insects themselves. Instead, you’ll see the symptoms of their feeding—twisted and curled leaves, yellowing foliage, stunted or dead shoots, and sluggish plant growth. Damage is usually most noticeable on shoot tips and new growth, along with unopened flower buds. When you take a closer look at these damaged plant parts, particularly on the undersides of young leaves and developing stems, you’ll likely find lots of aphids crowded together. These insects range in color from green to yellow, brown, red, or even black. Aphids cause damage by sucking sap from tender plant parts. As they feast, they excrete a sugary substance called honeydew. A fungus called sooty mold grows on the honeydew and blocks light from your plant, but is otherwise harmless. You can wash your plant leaves with water to get rid of the honeydew and sooty mold.
How to Get Rid of Aphids
When an aphid population explodes and begins to cause noticeable damage to leaves, stems, and buds, it’s time to act right away. The sooner you can deal with the infestation, the better chance you have of stopping the pests in their tracks and saving your plants from the point of no return.
Spray with Water
The safest and fastest way to control aphids is to spray them off your plants with a strong stream of water from the garden hose. Aphids are such small, soft-bodied insects that even a good rainstorm can knock them off. Once aphids are knocked off a plant, they rarely climb back on.
Insecticidal Soaps and Horticultural Oil
These controls are low-risk to people and the environment, but you still need to follow the label instructions. They’ll kill aphids, but must be applied on a regular basis during heavy infestations, since aphids reproduce so quickly. Insecticidal soap ($6, The Home Depot) and horticultural oil ($18, Walmart) only kill aphids when they come in direct contact, so you’ll need to reapply frequently until the pests are completely gone. And don’t forget to spray the undersides of leaves as well as the top. Keep in mind that insecticidal soaps and horticultural oil will kill beneficial insects as well, so only apply it to target pests.
Crush Aphids With Your Fingers
If you aren’t the squeamish sort, and the infestation isn’t so heavy that it would take forever to clean off, gently rub your thumb and fingertips over your plants’ leaves and stems wherever you see aphids. Remember, these insects are very soft and delicate, so they’re crushed with just light pressure. This tactic probably won’t completely eliminate every bug, but it can help enough so that your plants will be able to grow healthy leaves again. Check back every few days to see if you need to repeat the procedure.
How to Prevent Aphids
Preventing large numbers of aphids from making themselves at home is possible. In addition to making sure your plants have the water, light, and nutrients they need for staying healthy, here are a few more ways to help keep aphid numbers down.
Use Row Covers in Your Vegetable Garden
In spring, protect young plants in your vegetable plot with floating row covers ($15, The Home Depot). These will keep aphids (and many other insect pests) out, but allow air, light, and moisture to reach your plants. Remove the row covers when your seedlings are several inches tall, or when temperatures heat up in summer.
Remove Weeds
You may be watching for aphids on your plants, but these insects can also get a foothold in your garden by infesting weeds. Then it’s only a matter of time before they spread to your vegetables and flowers, so be diligent and keep up with weeding around your plants. Some weeds, such as sow thistle and mustard, appear to be especially attractive to aphids.
Attract Beneficial Insects That Eat Aphids
Plant flowers, including marigolds, calendula, sunflower, daisy, alyssum, or dill nearby to attract beneficial insects that love to feed on aphids. Ladybugs and lacewings are especially effective at devouring them.
