Woolly Apple Aphid

Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Superorder	Paraneoptera
Order	Hemiptera
Suborder	Sternorrhyncha
Infraorder	Aphidomorpha
Superfamily	Aphidoidea
Family	Aphididae
Subfamily	Eriosomatinae
Genus	Eriosoma

Scientific Name

Eriosoma lanigerum

Common Name

woolly apple aphid

Compiled by Whitney Cranshaw, Colorado State University

Eriosoma lanigerum (Hausmann)
Homoptera: Eriosomatidae

Hosts:

Apple, crabapple, mountain-ash, elm

Damage and Diagnosis:

Feeding on elm leaves and buds in spring cause the leaves to curl into closed, stunted clusters or rosettes at the twig tips. Curled leaves enclose colonies, protecting them somewhat from predators and insecticides. The aphids usually have left elm by late June but return and may occur in high numbers in late summer and early fall on elm leaves.

The more severe injury is caused by the insect feeding on the roots of apple, crabapple, and mountain-ash, resulting in large knots (galls) on the roots. Heavily infested trees often have short, fibrous roots, and are stunted and sometimes killed. Callous tissue around aboveground wounds are also commonly infested, which inhibits healing and can produce cankers.

Life History and Habits:

Life cycle.

The complete life cycle requires one year to complete, involving both a winter host of elm and summer hosts of apple, crabapple, or mountain-ash. Most Eriosoma species spend the winter as eggs in cracks and crevices of elm bark. However, in warmer locations or protected sites some nymphs can survive on the roots of apple. The eggs hatch in early spring and the young aphids move to the unfolding leaves and buds to feed and reproduce. After two wingless generations on elm, a winged generation follows, which migrates to the summer hosts (apple, crabapple, mountain-ash) where it feeds below ground on the roots and trunk or around wounds on the trunk. In the fall, a generation of males and females occur on elm which mate and produce an egg laying form. Each female lays one egg and dies. Four or more generations per year.

Related Species:

Related species also wintering on elm have alternative summer hosts. Eriosoma crataegi (Oestlund) is found on hawthorn and E. americanum (Riley) on amelanchier during the summer. On elm E. americanum produces a tight leaf curl in spring that is packed with aphids.

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