Pest description and damage Phylloxerids are very small (0.01 to 0.02 inch) aphid-like insects that lack cornicles. They are usually spiny in appearance and found in clusters. Winged forms have reduced wing venation. They attack the foliage and buds of red and white oak trees of all sizes. Buds and young developing leaves (undersurface) on terminals and branch ends are attacked, causing bright yellow spots and leaf distortion. Growth may be reduced or stopped and trees defoliated. Mature and nearly mature leaves are unaffected. Damage occurs during spring and early summer.
Pest monitoring Early detection on foliage will allow time to decide which/if management options will be useful.
Natural controls usually keep damage to a minimum. There are 10 species of predators recorded as feeding on oak phylloxera; however, at times significant damage and defoliation may occur and ornamentals may require chemical control.
For more information
Antonelli, A.L. and J. Glass. 2002. Oak leaf phylloxeran. (http://www.puyallup.wsu.edu/plantclinic/resources/pdf/pls118oakleafphyll...)