Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), is an oligophagous herbivore that feeds on several plant species in the family Solanaceae. Cannibalism is common in this species and accounts for a significant part of natural field mortality.We investigated effects of feeding on potato (Solanum tuberosum L., preferred host), tomato (Solanum lycopersicum L., nonpreferred host), and pothos [Epipremnum aureum (Linden & Andre) Bunting (Araceae), non-host] leaves on the incidence of adult Colorado potato beetles predating each other. After 48 h of confinement in laboratory arenas, significantly higher cannibalism was observed in the absence of host vegetation than in the presence of either potato or tomato leaves. After 72 h, more beetles were attacked when kept on tomato leaves than on potato leaves. Being confined on non-host pothos leaves led to higher cannibalism compared to either species of host plant. However, its incidence was lower compared to the no-leaf treatment, probably because pothos leaves served as a source of water. Our results suggest that adult cannibalism in the Colorado potato beetle may be triggered by a relatively mild adversity, but its extent increases as conditions deteriorate.