2 
Psyche 
[March 
food by a very large percentage of the species. This is 
paralleled almost nowhere else in the animal or plant king- 
doms, with the notable exception of certain parasitic or- 
ganisms. In the case of these parasitic types, such as path- 
ogenic bacteria, fungi and worms, it has of course never 
been questioned that they are important factors in influ- 
encing the abundance, distribution and, finally, the evolu- 
tion of their hosts and of competing organisms. The same 
is self-evident with respect to parasitic insects, including 
those that carry diseases, and the recognition of the role 
played by entomophagous parasites has led to the develop- 
ment of the method of biological control that we have ap- 
plied with success to the reduction of noxious insects. Such 
facts are so generally appreciated that we must not allow 
them to draw our attention at the present time from the 
less patent relationships that I wish to discuss. 
The conventional classification of food habits as first 
applied to vertebrate animals, and later extended to other 
less familiar groups may be readily applied to insects and 
we may thus more or less accurately group them in the 
following categories which are by no means either clear- 
cut or mutually exclusive, since they may grade into one 
another or appear in combination in the diet of a single 
species of insect. 
Omnivorous = Pantophagous 
Herbivorous — Phytophagous 
PUTRIVOROUS = SAPROPHAGOUS 
minimivorous = microphagous 
fungivorous = mycetophagous 
Carnivorous = Zoophagous 
predatory — harpactophagous 
parasitic = biophagous 
So far as insects are concerned it is difficult to arrange 
these in any linear order and certainly no single arrange- 
ment could be made which would indicate the phylogenetic 
sequence of the different types in the several major groups 
where they occur. Every type except the parasitic one is 
to be found among the most generalized groups of insects. 
Thus, the omnivorous cockroach, the vegetarian walking 
stick, or the predatory dragonfly are to-day emulating their 
forebears who feasted likewise in the forests of carbon- 
iferous times. 
