How to get aphids in your yard under control

The new growth of some of my honeysuckle vines and some of my perennials look funny, with bent-over stems and crinkled-up leaves. It looks like there are clusters of small bugs. What should I do about this?

— Sonya Patel, Naperville

Your description sounds a lot like aphids that seem to be more prevalent this year. Aphids may be green, black, brown, red, pink, or some other color. They are pear-shaped, slow-moving and range in size from 1/16- to 1/8-inch long. They feed on many different types of plants. Aphids are sucking insects that draw large quantities of plant sap, causing leaves and stems to become distorted. Crumpling leaves and bending tips at the tops of plants are indicators of aphids. Some of the plant sap will be excreted as honeydew, which makes the plant, as well as things like lawn furniture under the plant, sticky. A black, sooty mold often grows in the honeydew and blackens stems, leaves and other surfaces. The black, sooty mold is another clue that there is an insect problem in your garden. Dense colonies of aphids can be found along stems or on the undersides of leaves. They are drawn to succulent new growth on plants. Several generations of aphids may occur, with populations building up quickly.

Aphids are pear-shaped, slow-moving and range in size from 1/16- to 1/8-inch long. They feed on many different types of plants.

In time, natural predators are likely to get the aphid outbreak under control. Whether to take any corrective action will depend on the amount of damage that is occurring to your plants. Just because you have an insect pest in your garden does not necessarily mean you need to spray an insecticide. Try washing the aphids off with a steady stream of water. Use your judgment on how aggressive to be with this so as not to damage the plant further. In some situations, I have simply pruned off the aphid-infested parts of the plant. If the aphid problem persists, consider spraying with an insecticidal soap that will help control them. Insecticidal soaps work only on contact with aphids and also kills beneficial insects, so it is best to use sparingly. Use the soaps in the cooler temperatures of the early morning or evening to minimize the potential for damaging plants with the spray. There are also other insecticides that can be used to control aphids when the infestation is severe and not responding to more gentle controls.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.

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