Parasitoid: An organism that, during its development, lives in or on the body of a single host individual, eventually killing that individual. Larra wasps, Ormia flies, and Steinernema nematodes are examples of parasitoids; note that the wasps and flies feed like this during their larval stages, while in the adult stages they feed on nectar of plants. Many people use the word parasite when they really mean parasitoid; this is unfortunate because it obscures the lethal effect of parasitoids.