Most Common Types
Aphids are of the superfamily Aphididea. They are also known as plant lice in the United States and greenflies, blackflies, or whiteflies in Great Britain.
What They Look Like
Aphids are very small, only 1.5mm to 3.5mm long. They are usually green but may also be yellow, black, red, or brown. The insects have soft bodies, long antennae, small eyes, and little abdominal tubes called cornicles. Aphids move very slowly and do not hop or jump.
Where They Live
Aphids are found in nearly every tropical and temperate habitat in the world from the United States to Africa and Australia. There are around 1,350 aphid species in North America alone.
Where They Nest
Aphids can reproduce asexually and multiply quickly. They are often wingless but most species develop wings when colonies become crowded. The wings let them migrate to new feeding areas. Aphids can be found feeding on plant stems, shoots, and leaves.
Steps to Prevent
In localized infestations aphids can be washed from plants with a steady stream of water. Lady bugs, parasitic wasps, and aphid lions are natural predators. To avoid aphid infestations do not use heavy applications of nitrogen fertilizer which attracts the insects.
Are They Harmful?
Aphids are sucking insects and among the worst group of plant pests. Low numbers are not usually damaging but millions of the insects can be found feeding on plant sap in farm fields. This causes plant stems and leaves to become distorted. The sap is excreted as sticky honeydew which attracts sooty mold further stressing plants. Some species also transmit viral plant diseases. Aphids cause serious damage to grain, cabbage, and apple crops and contribute to hickory, alder, and beech tree blights.