Parasitism of insects

Abstract

Introduction: In general we may say that a parasite is an animal which lives at the expense of another, but this would not include many species which are commonly considered as parasites and which, while dependant upon a host animal for existence take nothing that is of value to the host. On the other hand, if we say the parasite is an animal dependent at some period of its life upon another for existence, we must include many forms which have none of the habits which we commonly associate with parasitism. Van Beneden has proposed three groups parasites, measurates and mutualists. In the first group are placed all those forms which feed upon the tissues of the host. In the second group are placed those which simply take the food collected by the host, but do not demand its own substance. In the third-group are placed those which simply ask protection or an opportunity to procure food in connection with, or to live upon cast off portions or rejected matter from the host.