Woolly Apple Aphid

Taxonomy

Kingdom:

Animalia

Phylum:

Arthropoda

Class:

Hexapoda (including Insecta)

Order:

Hemiptera

Family:

Aphididae

Genus:

Eriosoma

Species:

E. lanigerum

Subspecies:

E. lanigerum

Scientific Name

Eriosoma lanigerum
(Hausmann, 1802)

Common Names

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.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.