IDENTIFICATION

Dozens of species of aphids may be found on shade trees and woody ornamental plants in Michigan. Aphids are small insects that range from 1/8 to 1/4 inch in length. Aphids come in a wide variety of colors, from bright orange to green or gray to red.

DAMAGE

Aphids feed on plants by sucking plant sap from the leaves, twigs or stems of plants. A high population of aphid insects can reduce the growth and vigor of the host plant. This injury is most common with stem or trunk infesting aphids. Aphids can also cause leaf curling injuries.

Most aphids also excrete a sweet, sticky substance called honeydew. The honeydew dripping from feeding aphids can be a nuisance – depending on what is under the plant they are feeding on. Also, sooty mold fungus often starts growing on the honeydew, producing a gray or black covering on the leaves. This mold is not damaging except that it can temporarily reduce photosynthesis of the leaves.

ANTS AND APHIDS

Ants feed on aphid produced honeydew. Ants even tend colonies of aphids and other honeydew producing insects, much like we do with cattle. Often the presence of ants crawling up trees or over foliage indicates that large numbers of aphids or other honeydew producing insects are feeding on the plant.

CONTROL

Many types of insects naturally prey upon Aphids. However in the urban environment this may not be the case and aphid populations can get quite large. Tree spraying and systemic treatments work well for aphid control. Also, overwintering eggs from aphids can be controlled by spraying trees with dormant oils in the early spring.

HOST TREES:

Aphids can occur on most varieties of landscape trees and shrubs.

SYMPTONS / IDENTIFICATION:

There are dozens of species of aphids which come in a wide variety of colors, from bright orange to green or gray to red. Aphids are small insects, ranging between 1 /8 to 1/4 inch in length. Aphids can cause leaf curling as a result of their feeding.

LIFE CYCLE:

Aphids overwinter as eggs on their host plants. The eggs hatch in the spring and some winged aphids may move to other plant species. In the summer aphids can give birth to live young at the rate of 1 -20 per day without mating. Consequently, aphid populations can increase rapidly. Aphids mate on the host plant at the end of the summer and the female lays the eggs on the host plant.

HOW TO CONTROL APHIDS ON TREES AND SHRUBS

Many types of insects naturally prey upon aphids. However in the urban environment this may not be the case.

Systemic treatments work well since the tree is absorbing the insecticide via the root system.

Contact treatments work well for control when the aphids are exposed and not protected under a curled leaf.

For overwintering eggs, aphids can be controlled with dormant oil in the spring.

Photo:  John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

Photo: John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

Photo: Louis-Michel Nageleisen, Département de la Santé des Forêts, Bugwood.org

Photo: Robert L. Anderson, USDA Forest Service, Bugwood.org