Young blackheaded fireworm,Rhopobota naevana(Hübner), feed on old leaves or, when available, new leaves of cranberry,Vaccinium macrocarponAiton. In laboratory choice experiments, first-instar caterpillars preferred new leaves to old leaves regardless of temperature and photoperiod or generation of larvae. In no-choice tests, more larvae died before feeding (61.4%) when exploring dormant cuttings with only old leaves than did those exploring growing cuttings (11.8%). Larvae continued to reject old leaves and climb to the top of shoots even when deprived of food. Duration of the first stadium was 65% longer on overwintered leaves compared with young leaves. Survival of larvae in commercial cranberry marshes was 4.9 times greater after new shoot growth than survival of larvae hatched before new growth.