484 THE AMERICAN NATURALIST. 
irritating secretions, would naturally be supposed by some 
writers to be avoided generally by nearly all birds, but tey 
are habitually eaten by many birds of the eastern United States. 
This would lead one to infer that protective adaptations in our 
country are not always so efficient in securing insects from birds 
as has been commonly held. 
The fact that beetles and other insects which are gaudily 
colored — and consequently are supposed to be protected from 
birds — are greedily devoured by many birds, appears to show 
that warning coloration is not always as efficient as alleged, 
and one is almost led to believe that, because of this ineffi- 
ciency of warning coloration in many cases, protective mimicry 
has heen in some instances overestimated. Even the theory 
of protective coloration in its restrictive sense, when pitted 
against some facts, apparently loses a little of its luster in 
certain cases; and we are forced to admit. that factors may 
exist which sometimes nullify its action, so that the alleged 
protective coloration is not the all-important factor in securing 
an insect from extermination, as some earlier naturalists have 
supposed, but that there are other equally important factors 
that demand consideration. That is to say, coloration is not 
all, but only one of the determining elements. 
