Crape Myrtle Aphids
Crape myrtles are among the most commonly planted trees in the Southeast. The two main pests are crape myrtle bark scale, which was covered recently, and crape myrtle aphid.
Crape myrtle aphids overwinter as eggs and hatch in April. For the rest of the summer crape myrtle aphids give birth to many nymphs. Large populations produce enough honeydew to completely coat leaves and other objects below, giving infested plants a sticky or shiny appearance. This is a nuisance when it comes to keeping decks and cars clean but also leads to black sooty mold growing on the tree leaves and stems (and the deck, lawn chairs, toys below). Black sooty mold is noticeable from affair and really detracts from the beautiful bark and form of the trees.
So, why do aphids go berserk? Many aphids, scales, mealybugs, and similar pests outbreak when their natural enemies are disrupted by the environment (heat, drought, pollution) or by insecticides. In many cases contact insecticides are better at killing predators and parasitoids that are actively moving around a landscape than pests which may be hunkered down in nooks and crannies. Pests often reproduce faster too. So, if they get a window of time with no natural enemies they can really achieve large populations.
Insecticides applied to landscape plants, including mosquito spraying, can kill natural enemies like lady beetles, lacewings, minute pirate bugs, and parasitoids. Without predators and parasitoids pest populations can grow unimpeded.