Experimental studies in insect parasitism III—host selection

Every parasite has a number, one or more, of host species which it will attack. The inclusion in this number of some species and the exclusion from it of others implies a process of selection on the part of the parasite which is usually known as “host selection.” That parasites do choose certain hosts from the larger number of animals available to them is a well-known fact; but why they choose those particular species and reject others remains unknown. That, indeed, is the principal problem of host selection—to discover the criteria used by a parasite in selecting its hosts.