OBTAINING BEET LEAFHOPPERS NONVIRULENT AS TO 
CURLY-TOP 
[PRELIMINARY PAPER] 
By C. F. Stahl, Scientific Assistant , Truck-Crop Insect Investigations, Bureau of Ento¬ 
mology, and Eubanks Carsnbr, Assistant Pathologist, Sugar-Plant Investigations, 
Bureau of Plant Industry, United States Department of Agriculture 
The beet leafhopper (Eutettix tenella Baker) is the only known agent 
capable of transmitting the disease of the sugar beet (Beta vulgaris) 
known as curly-top. The fact that under some conditions, when col¬ 
lected from wild vegetation, the insects of this species failed to occasion 
the beet disease until they had fed on diseased plants was first shown by 
Boncquet and Hartung 1 and later confirmed by Smith and Boncquet. 2 
Experiments which had been started previously by Stahl to determine 
whether or not a leafhopper which has never fed on beets affected with 
curly-top will produce the disease proved the point, which was inferred 
from the discovery mentioned above, that it will not. Further tests 
made by the present writers to verify the earlier results have led to the 
development of the method, here to be described, of obtaining nonvirulent 
leafhoppers with certainty and relative ease. 
The manner in which the egg of the leafhopper hatches makes it possi¬ 
ble to remove the young nymph from the diseased to a healthy plant 
before it has had an opportunity to feed. The eggs are laid mainly in 
the petioles and midribs of the leaves. In the process of hatching the 
nymph forces its way, anterior end first, from the egg case and through 
the slit of the ovipositor. This is accomplished by an undulating move¬ 
ment of the body. Emergence from the egg membrane is practically 
complete, and the body of the insect reaches a position more or less per¬ 
pendicular to the plant surface before the appendages begin to unfold. 
As the appendages unfold the contortions of the body become more 
vigorous until the young nymph gains a foothold on the substratum. 
It is then able to free itself entirely from the egg membrane. The 
process is completed after from 5 to 16 minutes. During the latter part 
of the operation, when the appendages are unfolding, the opportunity is 
afforded of lifting the nymph off and transferring it to a healthy plant. 
Its transfer can be best effected by means of a small camel’s-hair brush. 
The first experiment, by Stahl, was begun on April 19, 1915. On that 
day three lots of nymphs, numbering 7, 9, and 15 individuals, respec- 
1 Boncquet, P. A., and Hartung, Wm, J. f the comparative effect upon sugar beets of eutet¬ 
tix TENELLA BAKER FROM WILD PLANTS AND FROM CURLY-TOP BEETS. In Phytopathology, V. 5, no. 6, 
p. 348-349. 1916. 
2 Smith, Ralph E.. and Boncquet, P. A. connection of a bacterial organism with curly leaf 
of sugar beet. In Phytopathology, v. 5, no. 6, p. 335-341. 1915. 
Journal of Agricultural Research, 
Washington, D. C. 
pd 4 
(393) 
Vot. XIV, No. 9 
Aug. 36,1918 
Key No. K-70 
