Trees at Risk
As the most common insect found on trees and shrubs and with over 350 different species, aphids feed on numerous species of trees. Some of the most common trees to be attacked by aphids include ash, birch, spruce, willow, apple, and elm trees.
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” long.
- Coloring is species-specific and 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.
Early detection is key in reducing infestations of aphids. 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.
Products for Treatment