40 



by the beaks of birds. Mr. Mosher watched the locality for a few days 

 and found many species of birds feeding on the caterpillars. He noticed 

 that whenever he left the locality many crows came in and fed. There 

 were very few parasites and other enemies of the gypsy moth in the 

 vicinity, and the conclusion naturally arrived at was that enormous 

 numbers of caterpillars had been destroyed by birds. Thus only could 

 the evident great reduction in the numbers of the caterpillars be ac- 

 counted for. Many birds were destroying the moth in all its forms, 

 and while they had not succeeded in suppressing the outbreak, it was 

 plain that they were exerting a strong restrictive influence upon the 

 increase and spread of this injurious insect. 



Recapitulation and Conclusion. 



It is to be regretted that it is impossible, because of lack of space, to 

 present in this brief paper more than a few of the carefully recorded 

 facts, through a comparison of which the following conclusions have 

 been reached, and it is hoped that another opportunity for publishing at 

 least a part of these recorded observations may offer. 



To recapitulate, — . 



(1) The widely accepted belief that hairy caterpillars have immu- 

 nity from the attacks of birds (excepting only the cuckoo) is erroneous. 



(2) This error has arisen partly from a lack of painstaking observa- 

 tion, partly from the inadequacy of stomach examinations alone to de- 

 termine the full value of many birds in this respect, and partly from the 

 well-known partiality evinced by many birds for smooth-skinned cater- 

 pillars. 



(3) During most of the time when the young birds receive their 

 food from the parents, they require a great quantity of animal food, 

 which consists mainly of caterpillars and other soft-bodied insects. 



(4) The parent birds, being overworked at that season in defending 

 their young from many enemies and in providing sufficient food both 

 for themselves and young, take such caterpillars as are most plentiful 

 and readily obtained. 



(5) The most destructive hairy caterpillai-s are gregarious, and 

 many of them reach their maximum of destructiveness usually when 

 many of the young birds are in the nests. The presence of these cat- 

 erpillars is marked by the evidence of their destructiveness. Their 

 presence is readily detected at a distance by birds, which visit places 

 where such food can be readily obtained in quantities. About forty 

 species are known to visit such places, feeding largely on the caterpil- 

 lars, while man}' of them take them to their young. When the young 

 are fledged they are led by the old birds to such localities and taught to 

 feed themselves. 



(6) An abundance of smooth-skinned caterpillars, which many 

 birds prefer, tends to limit the destruction of hairy caterpillars by birds. 



(7) Birds as a class must be considered as a potent factor in regu- 

 lating the increase of those moths whose caterpillars are covered with 

 hairs or spines. Many outbreaks of such species are " nipped in the 

 bud " by birds, and they have a large share in the repression of the 

 greater outbreaks. 



(8) As certain hairy caterpillars are among the worst pests known 

 to the farmers and fruit growers, those birds which destroy such cater- 

 pillars, and which are also in other ways to be considered among our 

 most useful species, should be protected, even if some of them take 

 small wages of fruit to pay for their services. 



