July 8 , 1918 
Toxoptera graminum in the South 
99 
developed into an oviparous female. From one of the oviparous forms in 
the A series a number of eggs were obtained but these eggs were infertile 
Fig. 2 .—Graph showing the comparative number of young of the individuals of 
Toxoptera graminum in the B series plotted against the date of birth of the indi¬ 
viduals. Columbia, S. C., March 23,1914, to April 26,1915. Solid lines represent 
the young of the first-born and broken lines the young of the last-born individuals. 
as no males had developed in any of the cages and none could be found 
in nature. The females lived for about one month. It seems entirely 
probable that if fertile eggs had been obtained they 
would have hatched either during warm days in win¬ 
ter or early the following spring. According to 
Webster and Phillips, 1 it is necessary for the eggs to 
be subjected to cold weather and freezes to make 
hatching possible. Freezes occur in the latitude of 
Columbia, S. C., although they are not so severe as 
are those in the region where the species was studied 
by Mr. Phillips; yet it seems possible that they were 
sufficiently severe to meet conditions necessary for 
the hatching of these eggs. 
COMPARATIVE NUMBER OF YOUNG OF INDI¬ 
VIDUALS IN THE DIFFERENT SERIES 
Fig, 3 — Graph showing com- A comparison of the number of young of the indi- 
Of the individuals of Toxo- viduals in the differents senes is shown in figures i 
tura trammum in the c to 3. The solid lines in these diagrams represent the 
date of birth of the indi- y° un g of the first-born and the broken lines the 
viduais. Columbia, s. c. young of the last-bo'm individuals. The largest 
191s. Solid lines represent number of young bom from any individual m the A 
the young of the first-bom series was 88, the reproductive period being only 22 
of the last-born indi- days. This individual was born during the month 
vtduais. 0 f April ,1913. During the following winter another 
individual gave birth to 82 young, the reproductive period in this case 
1 Webster, F. M., and Phiuips, W. J. op. cit. 
57665°—18 - 3 
££ 
Awen. | May 
