﻿THE GRAPE LEAFIIOPPER IN THE LAKE ERIE VALLEY. 21 



HATCHING OK FIRST-BROOD NYMPHS. 



After the finding of eggs in the tissue of the leaves on June 10, daily 

 examinations of infested grape foliage were made both in badly 

 infested vineyards and on vines at the laboratory. On June 18 three 

 nymphs were found on the badly infested foliage of a Delaware grape- 

 vine. These nymphs were probably about a day or two old, since 

 they were slightly larger than newly hatched nymphs. They had 

 taken on a yellowish color, which indicated that some time had been 

 spent in feeding, for the newly hatched nymphs before having taken 

 any food are white. 



On June 20 a number of newly hatched nymphs were found on 

 Concord vines. After June 20 the hatching of the nymphs became 

 general. By June 26 large numbers of them could be found in all 

 badly infested vineyards in the vicinity of North East, Pa. 



The process of hatching was observed in several instances and 

 occupies a -period varying from 10 to 25 minutes. 



The hatching nymph appears as a small white object projecting 

 through the pubescence on the underside of the leaf. At first its 

 movement is almost imperceptible. Then, after three or four min- 

 utes, there is a swaying circular movement of the free end of this white 

 object, each succeeding movement becoming more vigorous. After 

 four or five minutes of this rapid motion the object commences to 

 assume a definite form. The ends of the antennae are freed, the eyes 

 become prominent, and the stricture dividing the thorax from the 

 abdomen may be distinguished. In a few minutes more the proboscis 

 and the legs may be seen moving, then the circulation of the body 

 fluids becomes visible through the transparent skin, and finally the 

 feet clutch the hairy pubescence of the leaf and the tiny insect draws 

 its abdomen free of the eggshell. By this time the body has dried, 

 and the nymph runs with a rather unsteady gait over the underside 

 of the leaf. Usually, however, its first excursion is a very short one, 

 for it soon settles down, inserts its minute proboscis into the leaf 

 tissue, and makes its first meal on the juices of its host plant. 



APPEARANCE OF FIRST-BROOD ADULTS. 



During the season of 1912 the first evidence of the appearance of a 

 new brood of adults occurred on July 12, when examinations of 

 nymphs in vineyards about North East, Pa., showed that at this date 

 an occasional nymph was making the last nymphal molt and devel- 

 oping wings. However, winged adults of this new brood were not 

 common in vineyards until from July 16 to 20, and even at the latter 

 date they did not represent more than 25 per cent of the total num- 

 ber of the new brood upon the foliage. In order to secure some of 

 these earliest transforming adults for the purpose of rearing a second 

 summer brood, about 150 of the oldest nymphs that could be found 



