10 
Psyche 
[March 
become solidly entrenched among the unassailable biological 
doctrines, after having further engaged the attention of a 
score of later naturalists. I mention it here not for discus- 
sion, but only to show the similarity to to views just ex- 
pressed concerning phytophagous insects and their food- 
plants. 
Really no time remains for the discussion of . the other 
types of food habits among insects which I had hoped to 
mention in connection with their biological interest. They 
would serve to clarify the statements already made, but 
since they might also cloud the issue somewhat and since 
they show how thoroughly the insects have exploited the 
world’s food supply they are more appropriately dealt with 
in connection with my concluding remarks on insect food 
as viewed from the human standpoint. 
From a purely human standpoint, we must regard every- 
thing as either beneficial or harmful, unless it appear to be 
utterly unimportant or indifferent and the scientific mind 
will not admit the third possiblity. As entomologists are 
prone to look upon insects in this light we may view them 
thus at the moment. 
Injurious Insects 
harmful to man directly 
harmful to useful plants 
harmful to useful animals 
a. harmful to useful insects 
Beneficial Insects 
destroyers of injurious insects 
destroyers of undesirable plants 
destroyers of obnoxious substances 
producers of useful substances. 
I think this classification reflects the usual attitude to- 
ward the economic relations of insects, and it serves well 
to emphasize the fact that the importance of every species 
is gauged by what it harms, injures or destroys, with the 
sole exception of the small handful of “producers” like the 
