Aphids are small (less than 1/4 inch), soft bodied insects that have sucking mouth parts. For some reason, they have traditionally been called "plant lice" even though they are no relation.

Some types of aphids feed on one species of plants only while others may feed on several different plant species. They have a somewhat complicated life cycles that may include females who can produce eggs without being fertilized by a male. Several generations of only females can be produced over one summer.

Wooly aphids cover themselves with a waxy substance that make them look like a small cotton ball.

As with most sucking insects the key symptoms include the yellowing of the foliage due to the extraction of the green molecule of chlorophyll. In the process of digesting the sap from a plant, aphids excrete a sticky substance called honeydew that falls on leaves below. This causes the leaves to take on a shiny appearance and may lead to the growth of a black, smokey colored fungus called sooty mold.

The best sign of an aphid infestation is the actual presence of the insect itself. Although small, aphids are easily seen with the unaided eye. They do move around but, while they are eating, they have their snout stuck into the plant tissue. Aphids will be found feeding on the bottom of leaves and on tender new plant shoots.

Aphids are generally not very destructive. If in large numbers, they may stress the plants by withdrawing the sap. So the best prevention is probably just to keep an eye on plants in your landscape that are usual hosts to them.


Fortunately, once they are discovered in large numbers on a plant, aphids are easy to control. Many commercial insecticides are labeled for this insect. Many other options would include the use of insecticidal soaps and other organic treatments.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

Types of Insects

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