Beetles pick up the spores of the fungus disease, as they live in diseased elm wood.
Winter is spent in the larval stage beneath the bark.
Adults emerge in the spring from under the bark of dead or dying elms and feed on the tender bark in twig crotches of healthy elms. Disease transmission takes place at this point when the fungus spores rub off and get into the tree's vascular system. After feeding, the beetles tunnel into the inner bark of dead or dying elms and lay their eggs in brood galleries. There is one generation each year. Iowa State University Extension, Ames, Iowa.