1915} Ecological Foundations of Applied Entomology 7 
In applied entomology this is all of course very obvious, 
and needs no elaboration; for the economic entomologist is an 
ecologist pure and simple, whether he calls himself so or not—a 
student primarily of the interactions of insects and men, of 
that part of the actions and ecology of insects by which the 
welfare of man is affected, of that part of the ecology of insects 
which overlaps upon the ecology of man and that part of the 
ecology of man which overlaps, or can be profitably made to 
overlap, upon the ecology of insects. And it is the human 
interest which predominates and controls; the motive to ap- 
plied entomology is primarily humanitarian. If there were no 
human interest to which entomology is applicable, there would 
be no applied entomology. 
Now, since the field of applied entomology is precisely and 
solely that part of ecology in general over which the ecology 
of man and that of insects is coincident; since it is simply the 
ecological area common to two classes which differ almost 
immeasurably in their endowments, general interests, and 
natural relations, it must be evident, a priori, that a knowledge 
of the broad field of ecology as a whole, and of its general aims, 
principles, processes, and products, is fundamental to the special 
studies of the economic entomologist. It is only in some such 
sense as this that we can properly speak of the ‘“‘ecological 
foundations of applied entomology” at all. The very sub- 
stance of applied entomology being ecological through and 
through, it can have a foundation in ecology only as a part is 
founded upon the whole, as an apex is founded upon a base, 
as special aspects and applications of a subject are based upon 
its general principles and its most comprehensive characters. 
It is my special task, therefore, to point out and illustrate some 
of the ways in which general ecology may be made helpful to 
applied entomological ecology, and, vice versa, ways in which 
applied entomology may be made useful—is already useful, 
indeed—to the student of general ecology. 
A distinguished dean and professor of agriculture in one of 
our leading universities told me quite lately that the great need 
of practical agriculture at the present time is nothing less than 
a scientific study of vegetable physiology—the physiology of 
the common crop plants—concerning which we know so little 
that is exact and exhaustive that even the so-called scientific 
