Insect Problems on Oak Trees in Houston, Texas

Oak Apple Gall

• Oak apple gall (Amphibolips confluent) is among the primary pest of a number of oak species including black oak, a Houston native. The insects are very small sized, dark wasps with flat, oval abdomens with globe-shaped larvae. The pests damage the trees by leading to premature leaf drop in oak trees. Infestations from the oak apple gall are more prevalent in the spring season at the time of new foliage growth. Oak apple gall is best controlled with the introduction of natural predators in the oak trees.

Spider Mites

• Spider mites (Oligonychus spp. and Eotetranychus spp.) are small, spider like, eight legged insects with sucking mouthparts. The insects are common in white and red oak, a native oak species of Houston and other areas of eastern Texas. The feeding by the insects is characterized by a chlorotic coloring on tree foliage gradually followed by yellowing or bronzing of leaves. As spider mite infestations increase in trees, the foliage starts to die from the damage. There is often the appearance of mat-like webbing on foliage and tree limbs that weakens the growth of the tree. Biological control with natural enemies is often an adequate control method for the pest. Use insecticide in cases of severe infestation.

Kermes Scale

• Kermes scale (Kermes spp.) are a common insect pest on a variety of oaks including white and red. Red oak are a native of the eastern Texas, Houston area as cited by the Texas A&M University Extension. Kermes scale adult females are gall-like and globular with a yellow brown to black color. The insects are 0.1 to 0.3 inches in diameter and are commonly found on branches, near buds and midribs and petioles of foliage. Insect infestation cause dieback of twigs and foliage and premature leaf drop. Kermes scale are controlled with the use of recommended insecticides.