BIRDS DISTRIBUTING THE MOTH. 239 



the work of extermination. As this work progresses, birds 

 become more and more useful as destroyers of the moth and 

 less dangerous as disseminators of the insect. 



There appears to be little if any danger of the distribu- 

 tion of fertile female gypsy moths by birds, for, though birds 

 have frequently been seen to carry the female moths a few 

 feet or yards, the observations of five years have not afforded 

 an instance of their carriage to a greater distance. The per- 

 fect moths are to be found only in midsummer and later, a 

 time when all of the larger and most of the smaller birds 

 have no young in the nest. 



It is not probable that the birds distribute the eggs of the 

 moth to any appreciable extent, though they undoubtedly 

 scatter them somewhat by pecking egg-clusters from the 

 trees. As it was known that many of the scattered eggs 

 hatch, when denuded of their hairy covering, it seemed im- 

 portant to determine whether birds would break the egg 

 shells in feeding on the eggs, and whether unbroken eggs 

 would pass through the digestive tract of a bird without in- 

 jury to the shell and hatch if left exposed under natural 

 conditions. Birds might thus distribute the moth as widely 

 as they are known to distribute certain plants by scattering 

 undigested seeds. A confined sparrow was fed upon the 

 eggs of the moth, and it was found that most of them were 

 broken by the bird's bill, or in the process of digestion ; yet 

 some were passed entire. A similar experiment was made 

 with the crow. As the crows would not eat the eggs of the 

 moth unless disguised in food more to their taste, these 

 eggs were inserted in the bodies of grasshoppers and other 

 large insects, and while thus covered were swallowed by the 

 crows. A small proportion of these eggs were passed with 

 the shell unbroken, but the life of the eggs appears to have 

 been destroyed, as they are now drying up. This indicates 

 that there is no danger of a distribution of living eggs to a 

 distance by egg-eating birds. 



Although, as has been shown, certain species of birds 

 undoubtedly assist in the distribution of the moth by carry- 

 ing the caterpillars about, birds do much to prevent distribu- 

 tion not only by reducing the numbers of the caterpillars, 

 but by capturing male moths in search of isolated females, 



