﻿THE GRAPE LEAFHOPPER IN THE LAKE ERIE VALLEY. 19 



NUMBER OF EGGS DEPOSITED BY AN OVERWINTERING FEMALE GRAPE 



LEAFHOPPER. 



On account of the great difficulty encountered in locating the eggs 

 of the grape leaf hopper, a record of the reproductive capacity of the 

 females was secured hy confining pairs of overwintering adults upon 

 small grapevines in an arc-light globe cage similar to that shown in 

 Plate II, figure 1, which had been protected from previous infestation, 

 the object being to determine the number of nymphs that appeared 

 on the vines. The pairs used for this purpose were among the first 

 to be found copulating and at a period before any oviposition had 

 taken place. Each pair of adults "was allowed to remain on the 

 vine until they died. To avoid the probability of the escape of the 

 adults, only a few examinations were made until the nymphs were 

 nearing the last molt. The parent adults were then removed and a 

 careful count was made of the nymphs found upon the foliage; then 

 the parent adults were returned to the cage until later examinations 

 were made, and this process was continued until the death of the par- 

 ent adults occurred. After the death of the adults a period equal to 

 the length of incubation of the eggs was allowed to elapse before the 

 final count for the last nymphs to appear was made. Four separate 

 experiments were started May 27 with copulating pairs of adults. 

 Removal of nymphs took place as shown in Table II. 



Table II. — Number of nymphs produced by a female grape leafhopper in confinement. 



Nymphs 

 1912. CAGE NO. I. removed. 



July 11 34 



July 17 ' 33 



July 25 36 



Total 103 



CAGE NO. II. 



July 11 49 



July 17 49 



July 25 33 



Aug. 1 8 



Total , 139 



CAGE NO. III. 



July 10 i 4 



July 11 56 



July 17 34 



July 25 18 



Aug. 1 1 



Total 113 



CAGE NO. IV. 



July 11 34 



July 17 33 



July 25 36 



Aug. 1.. 9 



Aug. 2 2 



Total 1 14 



1 Four newly molted adults. 



