Woolly aphids

Definition

Aphids of the subfamily Eriosomatinae (family Aphididae), characterized by dense, filamentous wax secretions that form a conspicuous woolly or cottony coating over the body. This wax protects against desiccation, predators, and parasitoids while masking the aphid's outline. Most species are gall-forming on woody hosts, with complex life cycles typically involving host alternation between a primary host (often Prunus or related Rosaceae) where sexual reproduction and egg-laying occur, and a secondary host (conifers, elms, or roots of various plants) where parthenogenetic generations feed. The waxy filaments are extruded through specialized tubular ducts and can be brushed off to reveal the dark, soft-bodied insect beneath.

Etymology

From 'woolly' describing the dense, sheep-like wax filaments, and 'aphid' from Latin aphis/aphides, a plant louse.

Example

The woolly apple aphid (Eriosoma lanigerum) forms dense colonies on apple roots and above-ground wounds, its white wax masses resembling fungal growth; the woolly elm aphid (Eriosoma americanum) alternates between American elm and serviceberry, causing leaf curl and shoot distortion.

Synonyms

• woolly aphids
• woolly plant lice
• blight aphids

Related Terms

• Eriosomatinae
• aphid
• gall aphid
• host alternation
• wax secretion
• Adelgidae
• Pineus
• Eriosoma
• Parthenogenesis
• stylet

Usage Notes

Strictly refers to Eriosomatinae, not to be confused with adelgids (family Adelgidae, e.g., balsam woolly adelgid Adelges piceae), which are superficially similar 'woolly' Sternorrhyncha but belong to a separate family and lack cornicles. The term is sometimes applied loosely to any waxy aphid, but specialists reserve it for Eriosomatinae. The wax coating complicates chemical control and identification; specimens are often examined after wax removal with solvent.