32 FOOD OF WARBLERS 



The flock seldom exceeded fifteen birds, mostly Blackpoll and 

 Myrtle Warblers. Before night the swarms of insects that had 

 been so numerous in the morning had dwindled so that it was 

 rather difficult for me to secure a specimen, although the birds still 

 found some. When I went there the next morning a single remain- 

 ing bird was still finding a few, but I could not see a specimen 

 nor have I seen one there since. 



In 1905 I returned to my home at Wareham, Massachusetts, 

 the first week in November, and found a flock of Myrtle Warblers 

 busily hunting over the limbs and twigs of some apple trees and 

 pear trees near my house. From the actions of the birds, I con- 

 cluded that they had discovered an outbreak of some pest, but at 

 first I could see nothing on the twigs that they were inspecting. 

 By watching them with the glass, however, I soon saw exactly 

 where they were finding food. Then by stepping up to a bird 

 quickly and driving it away before it could seize the object of its 

 quest, I saw that it was feeding on a minute cicada-shaped, black 

 insect. This, indeed, was the only species of living insect I could 

 find on those trees. Three of these insects were secured, and two 

 were sent to Dr. L. O. Howard, chief of the Bureau of Entomol- 

 ogy at Washington. He identified them as the imago of the pear- 

 tree Psylla, a pest which has been very destructive to pear orchards 

 in Maryland and New Jersey. I learned that the birds had been 

 visiting these trees for about two weeks. At the time of my 

 return they had evidently disposed of most of the last brood of 

 the season, for, although they were still finding a good many on 

 the day of my return, they found very few afterwards though they 

 visited the trees daily for a week longer. These insects hibernate 

 on the trees by hiding in the crevices between the twigs and are 

 thus exposed to the attacks of birds all winter. The above brief 

 and imperfect review represents fairly well our knowledge of the 

 economic relations of American Warblers. Probably we shall 

 never have an authentic and scientifically accurate account of the 

 percentages of the component parts of the food of each species, 

 until the investigation of their food is taken up by the Division 

 of Biological Survey of the United States Department of Agricul- 

 ture, where the greatest study of the food of birds the world has 

 ever seen is now being made. Enough is known, however, to war- 

 rant the belief that our Warblers are deserving of all the pro- 

 tection man can afford them. 



