Crape myrtle (Lagerstroemia spp.) is a group of flowering trees and shrubs growing up to 30 feet high and 25 feet wide depending on the cultivar. These plants are easy-care in USDA hardiness zones 6 through 10, though they may die back in the winter in Zone 6. A few insects use crape myrtle as a food source; many others, however, stop by a crape myrtle to hunt.
Crapemyrtle aphids are about 1/16-inch-long, green-yellow, pear-shaped insects with black spots. They feed exclusively on crape myrtle, where they using piercing mouthparts to suck sap directly from leaves. Feeding leads to the excretion of honeydew, a sticky by-product of aphid digestion. Ants often protect aphids from their enemies in exchange for this waste product. Bait ants to allow predatory insects to move in and control aphids or spray with horticultural oil after the leaves drop in the fall. Aphid-resistant cultivars include "Acoma," "Caddo," "Fantasy," "Miami," "Sioux," "Wichita" and "Zumi."
The glassy-winged sharpshooter (Homalodisca vitripennis) is a narrow, 1/2-inch-long, brown to black insect with clear wings. It feeds on a range of plants, including crape myrtle, where it does very little visual damage to the plant. However, glass-winged sharpshooters are vectors of the bacteria Xylella fastidiosa, which causes bacterial scorch. Most pest management programs aim to preserve natural predators of the insect in question, but because X. fastidiosa is so damaging, aggressive pesticide use is suggested in areas where glassy-winged sharpshooters are invasive. Use a soil-application formulation of imidacloprid.
Florida Wax Scale
Florida wax scale (Ceroplastes floridensis) are about 1/8-inch-long, immobile red insects coated in a white, waxy material. Adults appear as waxy growths on the underside of crape myrtle leaves. Like aphids, scale exude honeydew, which then attracts protective ants. Prune out any heavily damaged or infested sections of the crape myrtle and burn them to destroy large numbers of scale. After baiting ants, control these sap-sucking scale insects by applying imidacloprid to the soil surrounding crape myrtle before eggs hatch in the spring. Acephate-based insecticide can be applied once eggs have hatched but will not be effective against adults that are encased in waxy coats.
Leptoglossus spp., the leaffooted plant bugs, are 3/4-inch-long, shield-shaped brown insects with exaggerated back legs resembling those of crickets. They feed on a wide range of plants, generally in a swarm. Leaffooted plant bugs are not usually considered a significant pest of crape myrtles, but can cause damage when feeding as a group on crape myrtle. Suggested insecticides require a permit for purchase or application, but this can be obtained by the home gardener. Use permethrin, bifenthrin or cyfluthrin as a contact foliar spray.
A number of beneficial insects are regularly seen hunting on crape myrtle plants. Lady beetles, lacewings, praying mantis and sugar-feeding ants are common sights in the garden. Tiny black parasitic wasps, bee-like hoverflies and a variety of assassin bugs, a half-inch to 1 inch long, are less common, but no less important, visitors to crape myrtle.
- University of California Statewide Integrated Pest Management Program: Crape Myrtle
- University of California Statewide Integrated Pest Management Program: Aphids
- North Carolina Cooperative Extension: Crapemyrtle Aphid
- University of California Statewide Integrated Pest Management Program: University of California Statewide Integrated Pest Management Program: Glassy-winged Sharpshooter
- Texas A&M AgriLife Extension: Florida Wax Scales: A Major Pest of Hollies and Other Landscape Shrubs and Trees
- University of Florida: Leaffooted Bug
- University of California Statewide Integrated Pest Management Program: Leaffooted Plant Bugs
- Clemson Cooperative Extension: Crape Myrtle
- Clemson Cooperative Extension: General Growth Requirements