29 



obseiwers at home and abroad in regard to this matter. The ornitholo- 

 gists of our national Department of Agriculture have added much to our 

 knowledge of the subject. 



The purpose of the present article is to furnish conclusive evidence 

 that the hah-s with which some caterpillars are armed are not a sufficient 

 protection to guard them from the attacks of birds, many of which eat 

 quantities of them and some also feed them to their young. It is also 

 intended to sIioav that many birds feed upon these insects later in the 

 chrysalis or in the imago. 



Those species of birds which feed upon hairy caterpillars are among 

 the best friends of the farmer and horticulturist, in so far as they prove 

 destructive to these insects, many of which are among the worst enemies 

 of farmers and fruit growers. 



When one attempts to disprove a theory which has been widely ac- 

 cepted for many years his readers are naturally inclined to be skeptical 

 as to his conclusions, and to question the accuracy of the observations on 

 which such conclusions are based. Therefore, a brief description of the 

 methods used and a statement of some of the results obtained will be 

 necessary here. 



During the progress of the work on the gypsy moth by the State 

 Board of Agriculture in Massachusetts more than a thousand men have 

 been employed, among whom there are, or have been, many who know 

 the common birds. Some of these men are keen-eyed observers. In the 

 early history of the work, when it was seen that birds were feeding on 

 the gypsy moth caterpillars, all those men employed who knew birds 

 were requested to watch the birds and report the results of their obser- 

 vations. There* were eleven such observers on the force at that time. 

 Others have joined the force from time to time, until the number whose 

 experiences have been recorded has been inci'eased to thirty-eight. 

 Some of these observers have seen birds feeding on the caterpillars of 

 the gypsy moth for only one season, others have been in the employ of 

 the Board for six, seven or eight years, and have made observations dur- 

 ing each year. The conditions have been such that most of the birds 

 could be observed within a few feet or a few yards. Those which could 

 not be so readily approached were watched with the aid of good field or 

 opera glasses, and where there appeared to be doubt birds were shot and 

 the contents of their stomachs carefully analyzed. 



Much was learned by experience in the earlier observations which has 

 been turned to good account in conducting those made during the last 

 three years. The value of such observations may be questioned by those 

 who rely solely upon the examination of the stomach contents to deter- 

 mine the food of birds. But for the purpose for which these observa- 

 tions are made they are, if skilfully conducted, quite as serviceable as 

 stomach examinations. In fact, one must supplement the other. 



Were one to follow the birds about through the fields and woods no 

 doubt some interesting facts might be learned in regard to their food, 

 but it is not in this way that a series of accurate observations can be 

 made. Birds are attracted to localities where insects are plentiful, pre- 

 ferring often to go some distance to such localities, where food is abun- 

 dant and readily obtained, rather than to search for less abundant species 

 near their nesting places. For our purpose, then, the method pursued 

 has been to find an outbreak of hairy caterpillars situated in a locality 

 where many species of birds would be likely to find it. The observer 

 first makes sure as to the kind of insects to be found upon the trees or 

 plants to be watched. He then conceals himself near the insects whose 

 destruction he wishes to observe and watches the birds which come there 

 to feed. 



When this method is followed methodically by trustworthy, pains- 

 taking observers, and when results obtained by different observers, 

 working independently, agree in the main, there can be no reasonable 

 doubt as to the value of such observations. When the caterpillars are 



