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The woolly elm aphid (''Eriosoma americanum'') is an 
The woolly elm aphid (''Eriosoma americanum'') is an aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
native to North America, found where Saskatoon (''Amelanchier alnifolia
''Amelanchier alnifolia'', the Saskatoon berry, Pacific serviceberry, western serviceberry, western shadbush, or western juneberry, is a shrub with an edible berry-like fruit, native to North America.
Description
It is a deciduous shrub or sma ...
)'' and American (''Ulmus americana
''Ulmus americana'', generally known as the American elm or, less commonly, as the white elm or water elm, is a species of elm native to eastern North America, naturally occurring from Nova Scotia west to Alberta and Montana, and south to Flor ...
)'' elm trees are established.
The aphid feeds on the Saskatoon elm in late spring through fall, and the American elm during both early spring and late fall.
Symptoms of American elm infestations include curled elm leaves, later accompanied by masses of visible dark areas and cottony masses. As with other aphids, honeydew may be found on infected leaves, excreted by the aphids after feeding on the plant's sap.
References
Eriosoma (aphid) Hemiptera of North America Insects described in 1879 {{Aphididae-stub