FECUNDITY OF WINGLESS VS. WINGED FEMALES. 75 
and as the individuals were isolated and protected as much as pos- 
sible from natural enemies it is probably safe to say that this average 
is as high as would obtain in the open fields, where they are convenient 
prey for their enemies. 
Mr. Urbahns found that in Texas the average number of young 
produced in the spring and fall was much greater than in the summer. 
The averages for December and January agree very well with those 
of the summer period. 
The maximum number of young produced by a single individual, 
under observation by Mr. Urbahns, that began reproducing in De- 
cember and January was 29, the average for this period being 17. 1; 
the maximum for those that began reproducing in April and May 
was 84, the average being 58.5 young; the maximum for those that 
began reproducing in June, July, and August was 39, the average 
being 17.2 young; the maximum for those individuals that began 
reproducing after August was 73; the average for the period from 
March to November is 39.7; the average for the entire number of 
individuals upon which Mr. Urbahns made observations during 1909, 
including the rearings during December and January, is 34 young. 
As will be observed, this is considerably above the average for 
Indiana. 
From the foregoing data it will be seen that the spring, in both 
the North and the South, is the most favorable period for reproduc- 
tion; in the North the summer period ranks next, the fall coming 
last, while in the South the summer is so hot that the aphidids can 
scarcely live at all, the fall ranking next to spring for productiveness. 
FECUNDITY OF WINGLESS VERSUS WINGED FEMALES. 
In 1890 the senior author gathered from his observations that the 
wingless forms were more prolific than the winged. In 1907 the 
junior author came to the same conclusion. In 1909 Mr. Urbahns, 
in Texas, observed that the winged forms did not appear to be so 
prolific as the wingless forms. During the summer of 1909, at La 
Fayette, Ind., the junior author carried on some experiments with a 
view of learning, if possible, something definite in regard to this 
matter. For this purpose 8 nymphs with wing pads and 8 larvae in 
the fourth stage were selected and each placed in a separate cage, 
each cage being placed under the same conditions. This experiment 
began on the 30th of August and all individuals became adult about 
the same time. The maximum number of young produced by a 
single winged individual was 44 and the minimum was 10; the maxi- 
mum number of young produced by a single wingless individual was 
61 and the minimum was 4. The total number of young produced 
by the 8 winged individuals was 224, or an average of 28 young for 
each individual; the total for the 8 wingless individuals was 274, or 
