Larger empty oak apple wasp

Larger empty oak apple wasp is an early season oak gall wasp. It occurs in the United States east of the Great Plains and in Ontario, Canada. It is usually identified by the gall it produces. The gall appears on a growing leaf of northern red oak in May. As the gall expands it may take over the entire leaf and falsely look like it is growing on the twig or leaf stalk (petiole). The fully developed gall is round, 1″ to 1½″ in diameter, bright green, glossy, and moderately to heavily covered with small red spots. Each spot covers a low, rounded bump (nipple). The outer walls of the gall are thin. The larval cell in the center of the gall is small. It is supported by filaments radiating in all directions from the cell to the gall walls.

The adult emerges in June. Late in the season the gall turns light brown.

Gall: 1″ to 1½″ in diameter

Spongy oak apple gall wasp (Amphibolips confluenta) galls are not spotted.

Oak gall wasp (Amphibolips cookii) galls are smaller, no more than 1″ in diameter. They protrude from a leaf bud, not a developing leaf.

June and July

Northern red oak