ADAPTIVE COLORATION 221 



the senses of the lower animals are co-extensive in range 

 with our own. As a matter of fact, birds detect insects with 

 a facility far superior to that of man, and destroy them by 

 the wholesale, in spite of protective coloration. Thus, as 

 Judd has ascertained, no less than three hundred species of 

 birds feed upon protectively colored grasshoppers, which they 

 destroy in immense numbers, and more than twenty species 

 prey upon the twig-like geometrid larvae; while the weevils 

 that look like particles of soil, and the green-striped caterpillars 

 that assimilate with the surrounding foliage are constantly to 

 be found in the stomachs of birds. 



After all, however, protective resemblance may be regarded 

 as advantageous upon the whole, even if it is ineffectual in 

 thousands of instances. An adaptation may be successful 

 even if it does fall short of perfection ; and it should be borne 

 in mind that the evolution of protective resemblances among 

 insects has probably been accompanied on the part of birds by 

 an increasing ability to discriminate these insects from their 

 surroundings. 



Warning Coloration. In strong contrast to the protec- 

 tively colored species, there are many insects which are so 

 vividly colored as to be extremely conspicuous amid their nat- 

 ural surroundings. Such are many Hemiptera (Lygceus, 

 Murgantia), Coleoptera (Necrophorus, Lampyridse, Coccinel- 

 lidae, Chrysomelidae), Hymenoptera (Mutillidae, Vespidae), 

 and numerous caterpillars and butterflies. Conspicuous col- 

 ors, being frequently -though not always associated with 

 qualities that render their possessors unpalatable or offensive 

 to birds or other enemies, are advantageous if, by insuring 

 ready recognition, they exempt their owners from attack. 



Efficiency of Warning Colors. Owing to much disagree- 

 ment as to the actual value of " warning " colors, several in- 

 vestigators have made many observations and experiments 

 upon the subject. Tests made by offering various conspicu- 

 ous insects to birds, lizards, frogs, monkeys and other insec- 

 tivorous animals have given diverse results, according to cir- 



