Pests and Diseases 197 
on seed, heating that seed to a dry temperature of 145° F. 
will kill any nematode without injuring the seed. 
The beet leafhopper (Eutettix tenella Baker). 
This is probably the most serious pest of the western 
sugar-beet. Plate XXIII. It causes injury through the 
disease curly-leaf, which it transmits. This disease, to- 
gether with all other similar leaf troubles, has gone under 
the general name of “curly top.” For many years the 
cause of this important disease was not known, but the 
discovery that it is due to punctures made in the leaf by 
the beet leafhopper makes clear the source of the difficulty. 
“Attention ! was first called to the trouble in 1899 and 
1900, when it appeared throughout the entire western 
region from California to Nebraska. Another serious 
outbreak occurred in 1905. Over the large part of the 
area it has only appeared two or three times in twenty 
years. In smaller areas it has usually appeared in three- 
year attacks, cumulative in nature, after which it has 
almost totally disappeared for a time. In still other 
areas it has appeared the greater part of the time, and in 
these areas beet-raising has not been successful. 
“This insect is single-brooded, hibernates as an adult, 
flies to the beet field in late spring, and lays eggs in beet 
stems — a few at a time until mid-summer. The larvae 
mature in summer and the adults disappear in early fall. 
It is found on shadscale, greasewood, Russian thistle, 
and fine-leaved annual salt bushes. Swarms of these 
insects appear suddenly in beet fields previously unin- 
fested. Much evidence points to the conclusion that these 
1 Ball, E. D., Utah Exp. Sta., Bul. No. 155 (1917). 
