cocKERELL] BIRDS AND BUTTERFLIES 21 1 



all day long with butterflies. One of the species caught, how- 

 ever, was Vanessa urticae (the tortoise-shell butterfly), which at 

 rest exhibits decidedly " cryptic " colors. Taking the whole of 

 the facts as presented, we are forced to admit that the opinion 

 that birds habitually eat butterflies to such an extent as to pro- 

 duce the results that current hypotheses demand, is much more a 

 ** pious opinion " than a statement of known facts. 



However, when we go again over the evidence, with a more 

 critical eye, there is one thing that strikes us at once. Nearly all 

 of it has been gleaned accidentally, at haphazard, as it were ; or 

 (in a minority of instances) is the result of careful observation 

 continued only for a very short time. Birds and butterflies are 

 everywhere ; but who has really gone at this problem seriously ? 

 Did the reader ever see a hawk catch a bird or a mouse ? Did he 

 ever see a butterfly hatch from the chrysalis in the wild state? — 

 there are many things which occur constantly all around us, to 

 our certain knowledge, but we do not see them. Naturalists are 

 not much better than others, for they are usually on the lookout 

 for their particular '' game," to the exclusion of everything else. 

 Who, in these busy days, will sit still somewhere for a couple of 

 hours, and just see what happens? Probably the most important 

 testimony, so far as it goes, is that of Mr. S. D. Judd, of the 

 Department of Agriculture, who has spent so much time examin- 

 ing the stomach-contents of birds. He says : '' I do not know of 

 a kind that feeds upon butterflies during any month of the year 

 to the extent of one-tenth of one per cent, of its food." It may 

 be urged, against this, that butterflies are hard to recognize in 

 birds' stomachs (the wings having usually been discarded), and 

 also, that a small per cent, of the food of a common bird means a 

 great many butterflies. 



I believe that the argument that birds are not often seen to 

 chase butterflies is a fallacious one. The flight of butterflies 

 usually protects them from capture on the wing, and the very fact 

 of the development of so many colors which are " cryptic " w^hen 

 the insect is at rest, points to the time of the greatest danger. 

 Who can find the butterflies on a dull day? Here is an exercise 

 for sharp eyes, and if followed up by taking photographs of the 

 resting insects among the foliage, would be both exciting and 

 profitable to science. 



Probably the best facts for or against the theories discussed are 



