478 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



are things to be modified and limited, just as the science itself is modi- 

 fied and limited. 



The use of entomophagous insects in economic entomology, while 

 not exactly a new branch of science, has experienced a considerable 

 development in recent years. This development has necessitated' 

 more careful biological work on entomophagous insects, and has in- 

 directly resulted in the adoption of a number of new terms to designate, 

 among other things, the many different types of host-relationships 

 exhibited. Manj^ of the terms having to do with insect parasitism 

 have "just growed." They have never been defined, and as they 

 originated at a time when our knowledge of the subject w-as much less 

 than at present, we find that they frequently include, under one name, 

 two or more distinct phenomena. In other cases two or more terms 

 have been used to designate the same phenomenon. The host-rela- 

 tionships of entomophagous insects is a subject of considerable com- 

 plexity and an accurate definition of the different types is essential 

 to a clear understanding of them. It has seemed to the writer that 

 to redefine the old terms now in use, to standardize, in a way, the ter- 

 minology of insect parasitism, would be to render a service to the 

 workers in that branch of entomology. In the following pages will 

 be found the writer's contribution, in so far as his limited knowledge 

 of the subject will permit, to such a redefinition. 



The term parasite itself is one of the most difficult to define and it 

 will not be attempted here. In this paper, when the term parasite is 

 used, it will be understood to refer to certain temporary entomopha- 

 gous insects onlj^, and not to those insects such as Mallophaga, etc., 

 which depend upon animals other than Arthropods for their subsist- 

 ence. 



In recent years there have appeared two papers,^ by Messrs. Fiske 

 and Pierce, in which certain phenomena connected with host-relations 

 were defined. These will be referred to frequently later on. 



Parasitism and Predatism 



The first and simplest division usually made of entomophagous 

 insects is based on their method of feeding. These divisions are 

 usually designated as parasitic insects and predaceous insects, and 

 these terms are generally used in what seems to be the correct sense. 

 A parasitic insect, in the generally accepted sense, is one which passes 

 its entire larval state within or upon a single individual host. A 



1 Fiske, W. F.: Superparasitism: An Important Factor in the Natural Control of 

 Insects, Jour. Econ. Ent., vol. Ill, pp. 88-97; Pierce, W. D.: On Some Phases of 

 Parasitism displayed by Insect Enemies of Weevils, Jour. Econ. Ent., vol. Ill, pp. 

 451-458. 



