1915] Ecological Foundations of Applied Entomology a 
if, among many other particulars the mere enumeration of 
which would quite exhaust your patience, we knew the facts 
concerning the temperature, light, and moisture of the air in 
different situations at different levels and during all seasons 
of the year. 
None of this matter is entomology, but it, and very much 
more of the kind, is entomological ecology, because it is an 
indispensable part of a description of the ecological environment 
of insects—of that part of the physical environment which 
enters into relations of cause and effect with the insect species 
which it environs. 
Would it not further help us greatly if we knew, or could 
readily learn in advance, even the more general facts concerning 
the reactions of insects and groups of insects, especially the 
economic species, to these various factors of their environment, 
as worked out under precise experiments verified by observa- 
tions in the field—their reactions in their several generations 
and in the various stages of their life history—and the effects 
upon their welfare of natural variations in these several environ- 
mental factors; if we knew also much more than now of the 
general relations of insects to the other organisms of their 
neighborhood, especially to those upon which they feed, and 
of the relations of these organisms and their products to the 
several factors of the physical environment? 
To me it seems so evident that such a knowledge would be 
of the greatest value to the investigating economic entomologist, 
that I am quite prepared to paraphrase the statement of Dean 
Davenport concerning the agricultural need of vegetable 
physiology by saying that the greatest need of applied entomol- 
ogy at the present time is just this kind of scientific ecology, and 
that it is among our first and most important duties to acquaint 
ourselves with this field and to encourage, provide for if possible, 
and assist as we can, serious, exact, and thoroughgoing work in 
scientific entomological ecology. 
It is now time, indeed, for me to say that entomologists in 
general are not lacking in an appreciation of these facts or in 
a cultivation of these interests; that, without waiting for the 
ecologists to bring grists to their mill, they have gone out into 
the fields and have harvested and threshed much grain for 
themselves; that they have of recent years done considerably 
more, I think, in entomological ecology than has been done by 
