CONTROL OF INSECT PESTS McATEE 417 



legislation protecting the animal in that State was passed at the 

 demand of the hop growers. Investigations in New Mexico by 

 the Biological Snrvey showed skunks also to be the most important 

 natural enemies of the range caterpillar. 



While we must confess that we do not know as much about the 

 food habits of vertebrates, other than birds, as we should know and as 

 we shall know when investigations now in progress are completed, 

 Ave can safely assert that no investigation is likely to upset the 

 present assumption that as enemies of insects, birds stand supreme 

 among vertebrates. If for no other reasons, Ave are thus confident 

 because birds are more numerous in species and individuals than 

 other insectivorous Aertebrates, and their greater mobility enables 

 them to concentrate quickly where unusual food supplies become 

 aA'ailable — that is, at the scene of insect outbreaks. 



The most extensive studies of the food of birds ever made hav3 

 been carried on by the United States Biological SurA'ey, but these 

 investigations for the most part haAC been directed toAvard learning 

 Avhat birds eat in general, rather than determining the explicit effect 

 of their food habits upon certain insects or other pests. The SurA^ey 

 has a great store of data as to the items of bird food, and the num- 

 bers and proportions in Avhich they are taken; it can furnish com- 

 prehensive lists of the bird enemies of a A^ast number of insects, but 

 it is not in a position to report from its OAvn resources, Avhat degree 

 of control birds attain OAer this or that particular insect pest. 



In fact opportunities to get such information come infrequently 

 and the observers most likely to be favored are the men in the field 

 who are working continuously upon an insect outbreak. These men, 

 usually, are economic entomologists, numbers of whom, fortunately, 

 liaA^e made good use of their opportunities, and it is largely upon 

 their work that the remainder of this article is based. The writer 

 is the more justified in quoting their findings so freely since economic 

 ornithology, not only in this, but in other countries, has been fostered 

 and inspired chiefly by entomologists. 



Among the earliest champions of the value of birds in this country 

 were Dr. William Le Baron, of Illinois, and Dr. Isaac P. Trimble, of 

 New Jersey, both well-known entomologists. These gentlemen did 

 not neglect the examination of tlie contents of bird stomachs, but it 

 may be a surprise to learn that Dr. ToAvnend GloA^er, first entomolo- 

 gist of the United States Department of Agriculture, not only ex- 

 amined the stomach contents of many birds, but had in the old agri- 

 cultural museum a collection of mounted birds Avith their food in 

 vials beside them. Furthermore, one of his annual reports, that for 

 1865, was devoted largely to a genoi-al account of the economic A^alue 

 of birds including results of his original investigations. The United 



