Pecan Phylloxeras are yellow- green swellings known as galls. They appear on the leaves nuts and shoots. These galls range in size to 1/8 inch to 1 inch in diameter. Shoots with these galls on them may be dying or weak. They will split open in the late spring, and when opened tiny soft bodied insects resembling aphids will appear inside. These insects are closely related to the aphids and are common pests of hickory and pecan trees. The eggs of the phylloxeras are laid in the fall and they live through the winter living on twigs and branches. The eggs will hatch when the leaves begin to bud in the spring. The insects that appear out of the eggs are called stem mothers. The stem mothers will feed on the new growth of the spring. These stem mothers inject a toxin into the leaves which produce rapid cell growth causing the galls. The galls eventually envelope the stem mothers, and after they mature they lay their eggs and die. When the eggs mature the galls spilt open and release the insects. This occurs in late May, or early June. These pests are most damaging to new growth in the spring!