Woolly elm aphid

Eriosoma americanum (Riley) (Hemiptera: Aphididae; Eriosomatinae)

Orientation to pest

Woolly elm aphid, Eriosoma americanum (Riley), is a native insect in North America whose primary hosts are American elm (Ulmus americana L.) and secondary, summer hosts are serviceberry (called saskatoon in Canada) and other species of Amelanchier spp. This aphid flies to elm in the fall where it mates and lays overwintering eggs. These hatch in the spring and nymphs feed on the edges of young elm leaves, causing them to roll inward and form a gall over the colony. In early summer, winged-forms migrate to Almelanchier species where they form colonies on the roots. Two other species of Eriosoma may also be found on elm, E. lanigerum (Hausmann) that causing terminal shoots to form rosettes and E. rileri Thomas, which forms woolly clusters on limbs and trunks. This aphid is a minor pest on Amelanchier alnifolia (Nutt.) Nutt., which is a fruit crop in Manitoba, Canada.

Hosts commonly attacked

American elm (U. americana) is the primary host and species of serviceberry (Amelanchier) are the alternative hosts.

Distribution in the USA

Woolly elm aphid is widely distributed throughout the eastern United States and Canada in the range of elm and serviceberry species.

Images of woolly elm aphid

Government of Alberta • Agriculture and Rural Development agriculture.alberta.ca 300x268	Whitney Cranshaw, Colorado State University, Bugwood.org 768x512 / 1536x1024
Figure 1. Winged adult of woolly elm aphid
Steven Katovich, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Figure 2. Elm leaf galled by woolly elm aphid	Figure 3. Stem of serviceberry infested by woolly elm aphid

Important biological control agents related to this pest species

Given this aphid's native status and limited damage, little is known about its natural enemies. In North America, some predators have been observed feeding on it, including the mirid Saileria irrorata Henry and the coccinellid Scymnus brulleri Mulsant.

Web links for information on woolly elm aphid

• BugwoodWiki Article | wiki.bugwood.org
• Fact Sheet | Manitoba Agriculture - Food and Rural Initiatives
  Provides information on biology of pest and its effect on saskatoon (A. alnifolia)

Articles

• Miranpuri, G. S. and G. G. Khachatourians. 1996. Bionomics and fungal control of woolly elm aphid, Eriosoma americanum (Riley) (Eriosomatidae: Homoptera) on Saskatoon berry, Amelanchier alinifolia. Journal of Insect Science 9: 33-37.
• Fry, K. M. 2001. Eriosoma americanum (Riley), woolly elm aphid (Homoptera: Pemphigidae), pp. 120-123. Mason, P. G. and J. T. Huber, J. T. (eds). Biological Control Programmes in Canada, 1981-2000. CABI Publishing, Wallingford, UK.