LEAFHOPPERS OF THE SUGAR BEET. 43 
found in this field, and in the fall the yield was nearly up to the 
average. This was the only field examined in which the leafhopper- 
did not appear until after the adults had hatched out. On the other 
hand, many fields were examined in which the leafhoppers had been 
present early in the season but had almost disappeared after the 
nymphs had matured, and yet in these fields the curling continued 
to develop throughout the season and the beets grew worse instead of 
recovering. 
Spraying with kerosene emulsion was tried on a field in the Cache 
Valley, Utah, in 1905. This field contained numerous adults and 
nymphs in all stages. Four nozzles were used, each one set about 18 
inches above the row and pointing obliquely down and forward, and 
just in front of them a bar drew the beet tops over and caused the 
leafhoppers to jump just as the spray struck them. An emulsion 
diluted with 15 parts of water had little effect on the adult.-, and 
only killed a few of the smaller nymphs. Most of the nymphs would 
kick about on the ground and some would become quite still, but a 
little later most of them would recover and hop away. An emulsion 
diluted with 8 parts of water produced the same effect on the adults 
that the weaker dilution did upon the nymphs, and killed the ma- 
jority of the nymphs that it struck. Many of the latter would, how- 
ever, escape the spray on account of the broad leaves of the beet, and 
the results were not considered entirely satisfactory. 
In the cage experiments it was expected that the number of leaf- 
hoppers necessary to cause " curly-leaf " on different-sized beets 
would be ascertained, but owing to the fineness of the gauze neces- 
sary to hold them the temperature and moisture could not be con- 
trolled and no ; ' curly-leaf " was produced. 5 The damp conditions of 
the cages also made it difficult to keep the insects for any length of 
time. 
In one experiment 1G leafhoppers. 12 of which were females ready 
to deposit eggs, were placed on a beet with a top 8 inches in diameter 
°This manuscript was originally prepared and submitted at the close of the 
season of 1906. Some revision was made to include the important farts of the 
work of 1907, but the main discussions, including the above paragraph, were 
written in 1906. since that writing " curly-leaf *' has appeared in cages arranged 
by Prof. E. 6. Titus in joint investigations with the writer. Mr. H. B. Shaw, 
assistant to Dr. C. O. Townsend, in charge of Sugar Beet Investigations, Bureau 
of Plant Industry, U. S. Department of Agriculture, lias also succeeded in pro- 
ducing "curly-leaf" under experimental conditions. He writes me under date of 
•October 23, 1908, that curly top or -curly-leaf" appeared in the cages on the 
experimental plat at Garland, Utah, in which lie Introduced the beet leaf- 
hoppers, and that later he sent a number of leafhoppers to the office i>t' Sugar 
Beel Investigations, Bureau i t Plant Industry, where •'• of them were placed in 
a cage with 11 young beets, «) of which showed distinct Symptoms of " curly- 
leaf" within five weeks after the insects were Introduced, 
