Crape Myrtle Aphids
DESCRIPTION OF THE PEST
Crape myrtle aphids are pale yellowish green in color with black spots on the abdomen. They vary in length from 1.5mm to 3mm long. They overwinter (survive the winter) as eggs, which hatch in the spring. During the growing season, females give birth to live young. Since it takes about 10 days to reach maturity, several generations are produced each growing season. At the end of the growing season, females produce eggs that overwinter.
Symptoms and damage
Aphids feed by inserting their mouthparts into tender new leaves from which they suck plant sap. Plant sap has a high sugar content. When they feed, the aphids excrete large amounts of sugary liquid called honeydew. With a large aphid population, the honeydew can completely coat leaves. The honeydew serves as food for the sooty mold fungi (Capnodium sp.), as well as various insects, including ants, wasps and flies.
As the aphid feeds, it injects saliva into the leaf. The saliva causes yellow spots to develop on the leaf. Their feeding on young leaves often causes distortion of leaves. Buds, branch tips and flowers can also be affected by feeding.
Several predators feed on the crape myrtle aphid. These include ladybird beetles (ladybugs) and their larvae (immature forms), green lacewings and their larvae, hover fly maggots, parasitic wasps and entomophagous (insect feeding) fungi. As much as possible, these natural predators should be allowed to reduce aphid populations. In addition, aphids can sometimes be removed from plants by spraying with a strong stream of water. Spraying with water may have to be repeated regularly, as needed.
As a result of their phenomenal reproductive rate, aphids are very difficult to control with insecticides. If a single aphid survives, a new colony can be produced in a short period of time. In addition, using insecticides means that beneficial predators will also be killed. If it is determined to be absolutely necessary, various insecticides are labeled for use by homeowners against aphids on crape myrtles. These include insecticidal soap, horticultural oil, pyrethrins, neem oil, permethrin, cyfluthrin, lambda cyhalothrin, acephate or malathion. Soil drenches of imidacloprid in the spring will control aphids and last longer within the plant to prevent future infestations by aphids and other insect pests .