﻿8 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 



During- the period from 1S97 to 1904 the writer of this paper resided 

 at Westfield, N. Y. ; during the summer months and had the opportu- 

 nity to observe the development of the outbreak of 1900 to 1904. 

 There was not a sudden appearance of this pest in a single season, but 

 a steady increase in numbers for several consecutive seasons preced- 

 ing the so-called outbreak of 1900. On the other hand, during the 

 summer of 1903 there was an apparent sudden disappearance of the 

 insect from many vineyards which during the two previous seasons had 

 been badly infested and suffered serious injury to the foliage during the 

 seasons of 1901 and 1902. In fact, after the season of 1904 this pest 

 disappeared from the vineyards of this area of serious infestation to 

 such an extent that treatment was deemed unnecessary. For several 

 years after this disappearance in destructive numbers of the insect 

 from the vineyards in the vicinity of Westfield, N. Y., its occurrence 

 in vineyards -throughout the Lake Erie Valley was not considered of 

 sufficient importance to warrant treatment. In 1909, however, during 

 the conduct of vineyard experiments at North East, Pa., the appear- 

 ance of this pest in injurious numbers was again observed in portions 

 of several widely separated vineyards throughout the township. In 

 the latter part of the season of 1910 the area of serious injury was 

 much more widespread and its increase was viewed with alarm by 

 vineyardists, and in the season of 1911 a number of the more pro- 

 gressive growers equipped themselves to fight the pest. During 1911 

 the injury wrought by the pest was greater than in preceding years, 

 and the infestation was more widespread. -The summer was unusually 

 hot, and this resulted in the development of an almost full second 

 brood which worked great injury to the vines late in the season. 

 Immense numbers of adults went into hibernation, and large numbers 

 of them emerged and made their appearance in the vineyards in the 

 spring of 1912. Early in the season of 1912, on account of the pres- 

 ence of so many overwintering adults, there was every indication that 

 the injury by this pest would be very great. There was an appar- 

 ently normal development of the first brood of nymphs, and by the 

 middle of the summer the injury in many vineyards was quite severe. 

 Fortunately, however, the months of July and August were unseason- 

 ably cool. The low temperatures which prevailed during these two 

 months so greatly retarded the development of the nymphs of the hrst 

 brood that only a small percentage of the adults transforming from 

 them deposited eggs for a second brood of nymphs. Hence there was 

 not such a great increase in numbers of the insect during the latter 

 end of the season of 1912 as there was at the end of the hot season of 

 1911. Nevertheless the injury done by this pest to many vineyards 

 was very great. The injury to the foliage, coupled with the coolness 

 of the summer, resulted in badly infested vineyards, in a retardation 

 of the cane growth, in a lack of proper development of the size of the 



