The beetle attacks all native and introduced species of elms. Identifying the Insect. The underside of the posterior is concave and armed with a prominent projection or spine on the undersurface of the abdomen. The larvae are typical, white or cream-colored, legless grubs, about the same size as adults. Identifying the Injury.
Larval mines are roughly perpendicular to the egg gallery.
The result is a design resembling a long-legged centipede on the inner bark and wood surface. Adults feed at twig crotches of healthy elms, infecting the tree with Dutch elm disease. Then they fly on to other elms for breeding. These attacked trees have usually been weakened by drought, disease, or other stress factors. After boring through the bark, the beetles excavate their egg galleries, grooving the inner bark and wood surface in the process.