﻿22 BULLETIN 19, TJ. S. DEPARTMENT OP AGRICULTURE. 



were placed on the foliage of a young Concord grapevine on July 12. 

 On July 13 several of these nymphs had transformed to adults. On 

 July 16 about 75 per cent of them had developed wings. 



MATING OF FIRST-BROOD ADULTS. 



On July 22 numerous pairs of adults of the new brood were found 

 copulating on the underside of grape leaves in the vineyards sur- 

 rounding North East, Pa. From July 23 to 27 copulating pairs of 

 new-brood adults were common, both in the vineyards and in cages 

 at the laboratory. After the latter date only occasional mating 

 pairs of adults were observed, either in the rearing cages at the 

 laboratory or in the open vineyards, although observations along 

 this line were continued during the remainder of the active season. 



NUMBER OF EGGS DEPOSITED BY A FEMALE OF THE FIRST BROOD. 



On July 26 three copulating pairs of the new-brood adults were 

 placed in separate cages on a Concord grapevine inclosed in an arc-light 

 globe cage similar to those in which pairs of overwintering adults had 

 been confined, the object being to ascertain the number of nymphs 

 that could be reared from them in order to see how it compared with 

 the number produced by overwintering females. The number of 

 nymphs reared from these first-brood females is shown in Table VI. 



Table VI. — Number of nymphs produced by a female leaf hopper of the first brood. 



cage no. r. 



Nymphs 

 Date examined (1912). removed. 



Sept. 4 12 



Sept. 7 5 



Sept. 11 7 



Sept. 14 , 9 



Total ' 33 



CAGE NO. II. 



Sept. 3 24 



Sept. 5 16 



Sept. 9 17 



Sept. 11 9 



Sept. 15 13 



Total ' 79 



CAGE NO. III. 



Sept. 4 37 



Sept. 7 35 



Sept. 11 9 



Total 81 



In the case of these three females of the first brood, the average 

 number of nymphs produced by a single female was only a little more 

 than half the number produced by the overwintering females under 

 similar conditions. 



