Crape Myrtle Aphids
Crape myrtles are among the most commonly planted trees in the Southeast. Fortunately, they do not have a lot of pests relative to some other landscape plants. The two main pests are crape myrtle bark scale which has not been reported in NC yet but is in Virginia and Tennessee. The other is crape myrtle aphid.
Crape myrtle aphids overwinter as eggs and hatch in April. For the rest of the summer
crape myrtle only feed crape myrtle. Since they feed on phloem –the sugary fluid produced by photosynthesis in the leaves – they produce a lot of sticky honeydew. Large populations produce enough honeydew to completely coat leaves and other objects below, giving infested plants a sticky or varnished appearance. Honeydew attracts ants, flies, wasps and other insects. Black sooty mold grows on honeydew making the leaves and stems black.
Crape myrtle aphids, and other aphids, attract a lot of generalist predators such as lady beetles, green lacewings, and minute pirate bugs that keep them in check. Unfortunately when these natural enemies are disrupted (read killed) crape myrtle aphids get out of control. We have noticed this happening as a consequence of mosquito spraying. The pyrethroids used by most mosquito operations kill natural enemies and could result in aphid outbreaks. I discuss that more in a blog post.