They are about half as wide as they are long.
Coloration is light brown or tan.
Because of variable color characteristics it is difficult to differentiate between the two species in the field. In the spring, adult loosestrife beetles chew holes in purple loosestrife leaves but do little real damage to the plant. Large numbers of newly emerged adults can cause further defoliation. Localized reductions in plant height and flowering may occur as early as the season following release. Typically it takes three to five years for populations of loosestrife beetles to build to levels that kill plants.