What is the meaning of "ideal parasite"? How can there ever be a totally harmless parasite? Parasitism is negative interaction, isn't it? Please explain.
an ideal parasite is the one which takes away the nutrition or energy synthesized by its host. ... The extent of harm done to the host differs with species of parasites. An organism is called a parasite because it causes harm to the host. If it stops doing that, it's no more a parasite