Saperda populnea

Long-horned beetles, (Saperda populnea L. or a closely related species) cause spherical or spindle-shaped stem galls (2 cm in diameter) on black cottonwood and on willows. Infestations are often heavy; the shape of the tree may be somewhat disfigured as a result. Adult females lay eggs in late spring in holes that they chew in the bark. When the egg hatches, the larva mines the cambium and then turns into the wood where it excavates a gall chamber. Growth from the wounded cambium causes the swelling. One or two adults emerge from each gall after one to two years of larval development. The adults feed on poplar leaves.

Saperda populnea

Oval twig gall, length 1.5 to 2 inches, beetle

Saperda populnea
[Page 65]

Hosts: cottonwoods and willows

Galls of this beetle are recognized by the hemispherical cuts (scars) made by adult beetles into which eggs are inserted between the phloem and xylem tissues.

HOST PLANTS
Salicaceae, oligophagous

Populus nigra, tremula, trichocarpa; Salix alba, aurita, caprea, x fragilis, apponum.