Aphids are small insects with pear-shaped bodies that usually form colonies on the undersides of the newest, most tender leaves and stems. Aphids vary in color depending on type. These insects use their sucking mouth parts to feed on plant sap. Heavily infested leaves can wilt or turn yellow due to sap removal. Healthy, established plants can tolerate low levels of aphid infestation. However, the saliva that some aphids inject as they feed can cause leaves to become wrinkled or distorted, and in some instances can cause distorted buds or fruit.

Many aphids produce large volumes of a sticky, liquid waste called "honeydew." Honeydew can make plant leaves appear shiny and attracts many flies, bees, and other insects. A sooty mold fungus can grow on the honeydew, turning leaves, stems, and branches black. Contact your local Extension office for insecticide recommendations.