Leaf Feeders
Robert F. Bassett, USDA Forest Service, Bugwood.org
Eastern tent caterpillar is a hairy black caterpillar with a white stripe down the back, brown and yellow lines along the side with a row of oval blue spots along the top line. The larvae live communally in silken tents. They feed for 4 to 6 weeks and may defoliate small trees. When mature, they wander to protected site to spin a cocoon. These tent caterpillars are active during April and May, there is one generation each year.
Lesley Ingram, Bugwood.org
The name, Pear slug, is a misnomer; these are not true slugs but sawfly larvae. The shiny, green to orange larvae can be up to a half inch long and feed by skeletonizing leaves. Larvae feed on the lower surface of pear, cherry and plum. There are two generations per year with overwintering occurring as a pupa. Adults emerge in early summer and lay eggs which mature, pupate and emerge as adults by August-September. New larvae from the summer generation will feed then pupate for the winter.
A. Steven Munson, USDA Forest Service, Bugwood.org
Fall cankerworm is a looper caterpillar that can vary from light green with yellow stripes to green with a dark stripe down the back. Overwintering masses of about 100 eggs hatch in later April or early May; small caterpillars chew small holes in young leaves at branch tips. Larger loopers leave only the midrib and major veins. Fall cankerworms are about an inch long when full grown. Mature larvae descend from trees on silk threads to pupate in the soil. They emerge as adults during periods of freezing temperatures to mate and lay eggs on host plants. There is one generation each year.
Sap Feeders
United States National Collection of Scale Insects Photographs,
USDA Agricultural Research Service, Bugwood.org
San Jose scale is one of the most destructive scale species. Infested stems, twigs or branches may be killed and heavily infested trees may die. These small circular brown armored scales have a series of dark concentric rings on their waxy covering. There are several generations each year. First crawlers are active from late May to early June, a second generation appears in late July and a third in late summer or early fall. Heavily infested plants may have a crusty covering of scales.
John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org
Aphids are soft-bodied insects that use their piercing sucking mouthparts to feed on plant sap. They usually occur in colonies on the undersides of tender terminal growth in the spring. Heavily-infested leaves can wilt or turn yellow and senesce prematurely because of excessive sap removal. While the plant may look bad, aphid feeding generally will not seriously harm healthy, established trees. Some plants are very sensitive to feeding by certain aphid species. Saliva injected into plants by these aphids may cause leaves to pucker or to become severely distorted, even if only a few aphids are present. Also, aphid feeding on flower buds and fruit can cause malformed flowers or fruit.
Aphids produce large amounts of a sugary liquid waste called "honeydew". The honeydew that drops from these insects can spot the windows and finish of cars parked under infested trees. A fungus called sooty mold can grow on honeydew deposits that accumulate on leaves and branches, turning them black. The appearance of sooty mold on plants may be the first time that an aphid infestation is noticed. The drops can attract other insects such as ants, flies, and wasps that will feed on the sticky deposits. For more information, see Entfact 103.