Defoliation by pests in the spring and early summer can result in net energy losses to the plant for the season. Repeated defoliations from season to season can cause loss of stored energy reserves. Branch and root die back may occur, possibly leading to the death of the tree. Managing pests to prevent extensive leaf loss early in the season is important in maintaining an actively growing plant. Late season defoliators have less impact on overall tree energy levels and growth.
Color is variable, ranging from yellow to green to black, depending on the species.
Populations of aphids can increase very rapidly due to their ability to bear live young and to reach the adult stage in as little as seven days. Often their colonies are found on new plant growth, clustering on the underside of the leaves. Aphids may be winged or wingless. They feed by sucking juices from the plant. Infested plants may lose their natural color, wilt, or become disfigured due to the aphid feeding.