Woolly Hawthorn Aphid – Eriosoma crataegi

Woolly Hawthorn Aphid – Eriosomacrataegi

Common Name: Woolly Hawthorn Aphid

Latin Name: Eriosomacrataegi


  • The adults of Eriosoma lanigerum are tiny to medium-sized aphids, up to 2mm long, with an elliptical form, and are reddish brown to purple. However, the color is generally disguised by the white cotton-like secretion from the aphid’s abdomen, giving it the popular woolly apple aphid.
  • The wax is created after each molt. Thus, newly molted individuals lack the wax coating. The wax coating’s primary purpose is assumed to be to prevent the honeydew emitted by the aphids from contaminating them. Still, it may also provide shelter from the weather, parasites, and predators.
  • It has six segments with sooty-brown antennae and tibias that range in color from dark brown to yellowish.This woolly material separates E. lanigerum from other apple tree aphids. Crawlers are in the earliest stages, and they do not create waxy filaments until they settle to feed.
  • The hibernating nymphs are very dark green, nearly black, yet they might be lighter and dingy yellowish-brown due to the lack of a produced white waxy cover.

Host plant: 

Apple, crabapple, and mountain ash, elm is a host plants.


  1. lanigerum is native to North America, but it is now widespread in every part of the world where apples are produced.

Damages caused by Woolly Hawthorn Aphid:

When elm leaves and buds are fed in the spring, they coil into closed, stunted clusters or rosettes at the twig tips. Curled leaves encircle colonies, shielding them from predators and pesticides. Aphids typically depart elm by late June, but they may return in large numbers on elm leaves in late summer and early fall. The bug is feeding on the roots of apples, crabapples, and mountain-ash causes more severe harm, resulting in huge knots (galls) on the bases. Trees that have been heavily infected frequently have short, fibrous roots, and they are stunted and occasionally die. Infested callous tissue around aboveground wounds is also prevalent, which hinders healing and can cause canker.

Life history and habits:

The entire life cycle takes one year and includes a winter host of elm and summer hosts of apple, crabapple, or mountain ash. Most Eriosoma species spend the winter as eggs in elm bark fissures and crevices. Early in the spring, the eggs hatch, and the young aphids migrate to the unfolding leaves and buds to eat and increase. Following two wingless generations on elm, a winged generation migrates to the summer hosts (apple, crabapple, mountain ash), where it feeds below ground on the roots and trunk or around wounds on the chest. On elm, a generation of males and females mate and generate an egg-laying form in the fall. Each female lays one egg before dying. Four or more generations every year.