ee ee ee ae i i 
’ s 
The Potato Leafhopper and Its Control. 11 
It has been found that two leafhoppers placed on an apple seedling 
covered by a cage caused “hopperburn”’ which killed the seedling 
in a short time (fig. 8). The same is true of bean plants. 
String, pole, and navy beans have been severely injured by “hop- 
perburn,” and if the plants were not killed the yields were greatly 
reduced. Lima and soy beans are not so heavily attacked nor is 
‘“hopperburn”’ ever severe on them, in Wisconsin at least. 
Sugar beets are liable to attack when grown adjacent to pota- 
toes, especially after the potatoes are nearly dead from “hopper- 
Fig. 9:—Sugar beets develop “hopperburn” when attacked by leaf- 
hoppers. Dead potato plants in adjacent row deserted by the leaf- 
hoppers. 
burn,” at which time there is a great migration of ‘‘ hoppers” from 
potato to beets. So far, however, ‘““hopperburn”’ has not become 
nearly as serious on sugar beets as on potatoes (fig. 9). 
NATURAL ENEMIES. 
Although there are three natural enemies of the potato leaf- 
hopper, none has become important as a control. One, a tiny 
insect parasite,” breeds in the leafhopper eggs, but does not occur 
in sufficient numbers to reduce noticeably the number of “‘ hoppers.” 
2 Probably a dryinid. 
