88 BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 



Individual egg deposition by migrants, recorded for 5 individuals, 

 was as follows: 3, 2, 1, 4, and 3: average, 2.6. Obviously the great 

 majority of migrants died without depositing eggs. The eggs above- 

 recorded were laid in from 2 to 9 days, the majority in from 3 to 5 

 days, after the migrants emerged from the nymphal skin. The great 

 majority of the migrants did not live more than 3 days after casting 

 their final molt, confinement evidently having caused premature 

 death. 



From 100 migrants produced August 15, 1912, and placed on a 

 small vine August 20, a single egg, which failed to develop, was 

 deposited August 21. 



In 1913 different types of cages were utilized in an effort to induce 

 a larger percentage of eggs and mature sexuals. The results were 

 not encouraging. From July 17 to October 17 migrants were placed 

 in the cages. During that time in some 60 experiments, 317 mi- 

 grants were used, 99 sexual eggs were secured, and 7 sexed phylloxera? 

 (all females) matured. The migrants in no case lived more than 

 6 days, the majority only 3 days, and quite a number did not move 

 their position after having been placed in the cages. In most cases 

 eggs were laid singly, but there was one group of 5, three groups 

 of 4, and several of 3 and 2, laid by single phylloxera?. In two cases 

 eggs, presumably of separate sexes, were deposited in the same group 

 by the same individual, but in all other cases it appeared certain 

 that the eggs laid by individual migrants were of only the one sex. 

 Judging from the size, about twice as many female as male eggs 

 were laid, besides quite a number (about 20 per cent) of eggs of an 

 intermediate size. No male or intermediate sized eggs hatched, but 

 it was noticed that the male eggs, as they developed, assumed a 

 darker color than did those of the female. After a certain point in 

 the development, all the moribund eggs began noticeably to shrink 

 and turn dark brown. None of the eggs showed signs of infertility, 

 and within about five days of deposition hatching occurred and the 

 eyes and body segmentation were visible, after which the moribund 

 individuals discolored and shrank rapidly. Dead migrants were 

 found occasionally on the roots and sides of the cellar jars, beside 

 eggs that they had deposited. In the vineyard such a procedure was 

 never observed, and therefore it is believed to be quite abnormal, and 

 probably results from the inability of the migrant to escape from the 

 cellar jar after having been overlooked in the periodical examinations 

 for migrants. 



During the summer of 1914 a further series of experiments on the 

 production of sexual eggs took place. The temperature that year 

 was considerably below that obtaining in the years 1911 and 1913, 

 and this may account for the lack of sexuals maturing. In 1914 the 

 cages utilized in 1913 and some of other types were employed. 



