Woolly aphids (subfamily: Eriosomatinae) 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.
Due to their appearance, they are occasionally given the nickname "Fairy Flies."
The woolly apple aphid is a pest for fruit growers. Many of the numerous species of woolly aphids have only one host plant species, or alternating generations on two specific hosts.
Further minor damage can be caused by the honeydew that woolly aphids secrete, which is difficult to remove. While the honeydew itself doesn't cause too much of a problem, the honeydew can cause sooty mold to grow, which can block some of the sunlight needed for photosynthesis.