VIVIPAROUS DEVELOPMENT IN SOUTH. 
47 
can not be sure of the species as they were not reared. Winged and 
wingless viviparous females (figs. 7, 8) were, however, present at the 
time the eggs were found, as were also those of both Aphis (Sipho- 
coryne 1 ) and Macrosiphum. Mr. E. Dwight Sanderson obtained the 
males and oviparous females of Macro siplium granaria Buckt. in 
Texas but only artificially in his rearing cages. Mr. R. A. Vickery, 
of this bureau, found males, females, and eggs of Aphis maidi-radicis 
Forbes at Salisbury, N. C. These instances mentioned above are 
probably the most southerly points at which oviparous forms of 
plant-lice have so 
far been found in 
the United States. 
In the Southern 
States, wherever 
there is sufficient 
food, Toxoptera 
apparently breeds 
viviparously 
throughout the 
year; for this rea- 
son the number of 
generations here, 
other things being 
equal, should far 
exceed that in the 
Northern States. 
As a matter of fact, 
however, the dry, 
hot, protracted 
summers of the 
Southwest are 
probably disas- 
trous to the species during the hot months, except perhaps in 
secluded nooks, where there is a supply of succulent host plants. 
In northern Texas, as observed by Mr. Urbahns, during June of 
1909, Toxoptera rapidly disappeared with the ripening of the grain 
crops and the approach of hot weather. Winged forms migrated 
with the breeze early in this month, and wingless forms soon perished 
from extreme heat and a shortage of green food in the field. Obser- 
vations clearly showed that it was almost impossible for the " green 
bug" to live and reproduce in grain fields during the summer. While 
1 Probably Siphocoryne avense Fab. The use of the generic name Siphocoryne, as applied to this species, 
is questionable, and is not at present followed by many, perhaps the major portion, of the students of the 
Aphididse. According to Schouteden (Ent. Soc. Belgique, vol. 12, p. 217, 1906, Catalogue Aphides de 
Belgique) it should be Aphis. Some of our best students, however, admit that this particular species, 
avense, is on the borderland between Siphocoryne and Aphis. 
Fig. 8. — The spring grain-aphis: Wingless viviparous female, 
actual size, 2 mm. (Original.) 
Enlarged; 
