Insects & Diseases Info

are sucking insects that live on plant fluids, and produces a filamentous waxy white covering which resembles cotton or wool. The adults are winged and move to new locations where they lay egg masses. The larvae often form large cottony masses on twigs, probably for protection from predators.

The wooly apple aphid is a pest for fruit growers. Many of the numerous species of wooly aphids have only one host plant species. Wooly aphids can produce lots of honeydew that coats the lower leaves and anything else beneath their hose plant. Wooly aphids look much like other aphids except they are white and fuzzy like mealybugs. Hy-Yield Kill-A-Bug or Ortho Insect Control with Orthene can either be used to control wooly aphids.

Woolly aphids generally have two hosts: a primary host on which they overwinter, and a secondary host on which they spend much of the summer. Most woolly aphids share a similar life cycle, although some details of the life cycle may vary among species. They usually overwinter as eggs laid in bark of their primary host. In spring, the eggs hatch into females which give birth without mating. Each female can produce hundreds of offspring, so populations can grow rapidly.

After one or two generations on the primary host, winged females are produced, and they fly to secondary hosts. They remain on secondary hosts for the remainder of the summer, producing several generations of young aphids. In late summer or early fall, a different group of winged females flies back to a primary host where they give birth to tiny male and female aphids that mate. Gravid females deposit a single large egg (or eggs) into protected locations in the bark and then die. While woolly aphids generally have two hosts, many species can sustain themselves on their secondary host alone (see below).

Woolly aphids feed by inserting needle-like mouthparts into plant tissue and withdrawing sap. They feed on leaves, buds, twigs, and bark, but can also feed on the roots. Symptoms of feeding include twisted and curled leaves, yellowed foliage, poor plant growth, low plant vigor, and branch dieback. Physical injury may result when large numbers of woolly aphids attack young trees or unhealthy, stressed trees. Fortunately, severe woolly aphid infestations only occur periodically and are generally kept in check by natural enemies. In addition to the physical damage to the plant, accumulations of wax and shed skins are sometimes very conspicuous signs on the leaves, twigs, and bark.