a parasite that ultimately destroys its host, as any of various wasp larvae which feed progressively on the tissues of an immature stage of a host species
Origin:
parasit(e) + -oid
See parasitoid in American Heritage Dictionary 4
noun
Any of various insects, such as the ichneumon fly, whose larvae are parasites that eventually kill their hosts.
adjective
Of or relating to a parasitic insect of this kind.