Aphids are the most common insect found on trees and shrubs. There are many species of aphids that feed on numerous hosts. Aphids use their piercing sucking mouthparts to extract sap from the tender, new growth of plants. While aphid feeding does not look good, it usually doesn’t cause serious damage to plants. However, aphids do excrete a sticky substance called honeydew that can be a real nuisance, as it gets all over sidewalks, vehicles, etc.
Early detection is the key in reducing infestations of aphid. Examine areas near the buds and on the undersides of the new leaves for aphids. When natural enemies, like the lady beetle, are not sufficient in keeping the population in check, insecticides are very effective for controlling aphids. Contact insecticides can be used on exposed aphids, but are not effective against species that develop in leaf curls. Soil applied systemic insecticides are also very effective and can be applied once in the fall or spring to deliver control throughout the growing season.
Use Xytect 10% as a tree injection treatment for trees that cannot be treated with foliar sprays or other systemic options.
Other Treatment Practices
Proper watering and the avoidance of heavy nitrogen fertilizer, which promotes succulent plant growth, can help reduce aphid damage.
Aphids are an easily controlled pest with most products when properly timed and applied correctly.
Signs of Damage
- Aphid feeding causes curled discolored leaves
- Feeding aphids excrete honeydew making the plant sticky
- A black fungus called sooty mold may be growing on the honeydew
- Aphids are slow moving, oval to pear-shaped insects ranging in size from 1/16 to 1/8 inch long
- Coloring may be black, brown, green, red, pink, or other color
- Pipe-like protrusions extending off the back of the insect are visible with a hand lens
- Some aphids have transparent wings
Photo: E. Bradford Walker
Vermont Department of Forests, Parks and Recreation, Bugwood.org
Photo: John A. Weidhass
Virginia Polytechnic Institute and State University, Bugwood.org
Photo: Albert (Bud) Mayfield
USDA Forest Service, Bugwood.org
Trees At Risk
As the most common insect found on trees and shrubs and with over 350 different species, there are numerous hosts for the aphids.
- Overwinter as eggs on hosts bark or needles.
- In spring the eggs hatch(100-250 GDD)and aphids migrate into summer hosts.
- In late summer eggs are laid again.
- Can be several overlapping generations per year.
University of California
University of Illinois
Colorado State University
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.