Aphids

The crape myrtle aphid (Tinocallis kahawaluokalani) is the primary insect pest of crape myrtle shrubs grown in Texas. Although these tiny, green and black pests reach no larger than 1/8 inch long, large aphid populations can cause a lot of damage. Aphids congregate beneath the leaves to feed by inserting their long, needle-like mouthparts into the plant tissue and sucking out the sap. As they feed, their saliva causes little yellow spots to form on the leaves. Prolonged feeding activity can cause a stunted plant as well as deformed leaves, flowers and buds. Despite this aesthetic damage, the feeding activity causes no long-term damage on crape myrtle shrubs.

Japanese Beetles

Japanese beetles (Popillia japonica) occasionally attack crape myrtle shrubs planted in Texas landscapes. The white, C-shaped, grub-like larvae live in the soil and feed on young roots, but typically don't cause any visible damage. Adult beetles have 1/3 to 1/2 inch long, metallic green bodies and copper-colored wings. The adults occasionally feed on flower buds, but prefer chewing on the leaf tissue that lies between the major veins. The feeding activity may give the leaves a lacy appearance or leave the foliage looking skeletonized.

Flea Beetles

Flea beetles enjoy feeding on crape myrtle plants, with primrose flea beetles (Altica litigata) most commonly appearing in Texas. These pests have shiny, bluish-green bodies that reach about 1/4 inch long and strong back legs that allow them to jump quickly whenever disturbed. Primrose flea beetle larvae live beneath the ground and feed on the roots, while the adult pests chew numerous holes into the leaves, often making the shrub look as if it were peppered with fine buckshot. Young crape myrtle shrubs are particularly vulnerable to feeding damage, and large flea beetle populations can cause reduced vigor, stunted plant growth and even death of the entire plant.

Nonchemical Control Methods

Naturally control crape myrtle pest populations by pruning off and discarding infested plant tissue. Regularly spraying your shrub with a strong stream of water from your garden hose can also reduce pest populations. Japanese beetles are large enough that you can often control populations by handpicking the pests off the foliage and dropping them into a bucket full of soapy water. The beetles prefer feeding in the warm sunshine, so search for the pests around noon for optimal handpicking results. Sucking up flea beetles in a handheld vacuum helps reduce populations, as does covering young shrubs with a lightweight covering.

Chemical Treatments

Chemical treatments are sometimes necessary to get rid of severe insect infestations on crape myrtle shrubs. According to the Texas A&M AgriLife website, using a neem oil spray can help treat all three of the major myrtle pests. Following the dosing and application instructions on the product's label, mix about 2 tablespoons of neem oil product into a gallon of water. Spray your shrub until it glistens with moisture. Repeat applications every seven to 14 days until the pests are gone.