154 USEFUL BIRDS. 



and the trunks of the trees appeared as if smoked. The 

 enormous secretion of honeydew that the hosts of these 

 insects produced from the sap of the trees fell like rain, 

 drenching the horses used in cultivating the orchard, and 

 running down the trunks in such quantities that it extended 

 in a discolored circle fi'om six to eight inches from the base 

 of each tree. This information comes from the above-men- 

 tioned circular. 



If the birds had been engaged for more than two weeks in 

 clearing these insects from the few pear trees about my home, 

 there must have been a great number of insects on those trees, 

 for the pests are so small that each bird might eat thousands 

 of them in a day. At the time of my return the insects were 

 evidently becoming scarce ; but the birds persevered in their 

 attentions to those trees, until in a few days I could not dis- 

 cover a single specimen of the insect ; but even after that they 

 looked the trees over occasionally, and still found a few. By 

 the end of another week, however, they had exhausted the 

 supply, and, although they were seen occasionally in the 

 woods, they seldom visited our trees. Apparently this was 

 an incipient outbreak of a pest, brood after brood of which 

 had probably been attacked by birds during the summer. 

 As autumn came on, and the summer "Warblers left on their 

 southern migration, the last brood developed. The late- 

 coming Warblers found them, and eagerly completed the task 

 left unfinished by the summer birds. The pear trees had con- 

 tinued to bear both foliage and fruit as usual, and showed 

 no injury. They will probably receive a similar protection 

 next year. 



Dr. Howard intimates in his bulletin that the causes 

 which control the increase and decrease in numbers of this 

 insect are not fully understood. Here js one agency of 

 control that we can understand. It would be interesting 

 to know to what extent this insect is distributed in Massa- 

 chusetts, and how much the birds are doing to control it. 

 These insects are so tiny as to escape observation, and this 

 episode would have passed unrecorded, like so many others 

 of its kind, had I remained away from home a few days 

 longer. 



