52 ANIMAL ACTIVITIES. 
its back a great number of pupa-cases of such flies is no 
uncommon sight (Fig. 67). Birds, too, devour im- 
mense numbers of insects in all stages of growth. 
Doubtless they would kill and eat all the insects were 
it not for the fact that many of them are so wonder- 
fully protected by their color or shape, or both. 
Protective Coloration. A butterfly or moth when 
pursued often disappears as if by magic, and only the 
most careful search reveals its presence. Then it is 
Fic. 53.—Catocala Nupta. 
seen that the insect has been rendered invisible, not 
by the helmet of Perseus, but by its resemblance to 
some natural object common in its vicinity. The 
Kallima, a large and brilliant butterfly of India, folds 
its wings and alights on a branch. The folding of the 
wings conceals every brilliant color, and the under side 
of the wing, which is now alone visible, resembles so 
accurately a leaf that a bird could find it only with 
great difficulty (Fig. 52). 
Some of our common moths, belonging to the genus 
Catocala, have outer wings so closely resembling the 
bark of birch-, poplar-, or willow-trees that when they 
alight on one of these trees they cannot be seen by a 
casual observer. Other cases of protective coloring are 
to be met with at every turn in the study of Zodlogy, 
and it is a part of the work of the student to find and 
describe them. 
