Woolly elm aphid gall - Eriosoma lanuginosum

Eriosoma lanuginosum (Hartig, 1839) is an aphid species which causes the formation of pseudogalls on Elm leaves. The elm balloon-gall aphid Eriosoma lanuginosum induces Ulmus trees to produce large bloated-leaf galls and several generations of wingless aphids live inside the growing gall until it fissures, permitting winged aphids to move to a different host (Blackman & Eastop, 2013).