28 MONTANA EXPERIMENT STATION BULLETIN 333 



In sections of Pondera and Phillips counties about 90 per 

 cent of the female moths were sterile so practically no eggs 

 were laid. 



Second Generation, 1936 



A heavy flight of moths was observed over practically the 

 entire state but, with the exception of the Triangle Area, a high 

 percentage of them was sterile, resulting in a very light second 

 generation of worms. Fergus, Judith Basin, and Blaine coun- 

 ties had second generation webworms in small numbers. 



The beet webworm since 1934 has been made the subject of 

 an exhaustive study by the Montana Agricultural Experiment 

 Station. Particular attention is being paid to improved methods 

 of control, to the possibilities of accurately forecasting out- 

 breaks, and to certain physiological and ecological factors which 

 are important from the control standpoint. 



BLISTER BEETLES 



A scourge to field beets, potatoes, gardens, and ornamentals 

 during 1935 and 1936, were various species of blister beetles 

 with the spotted blister beetle (Epicauta maculata Say) pre- 

 dominant. Thousands of acres of beets v/ere lost because of 

 these insects and more damage would have resulted had not 

 arsenical sprays and dusts been employed. A rise in the number 

 of blister beetles always accompanies years of grasshopper abun- 

 dance because, in the larval stage, the blister beetles feed on 

 grasshopper eggs. 



THE FALSE CHINCH BUG 



In point of numbers this small insect, a close relative to the 

 true chinch bug, was the greatest pest in irrigated sections of 

 Montana in 1936. In the lower Yellowstone country potatoes 

 were severely injured and often stunted to the point of crop 

 failure by heavy swarms of these tiny insects. The wingless 

 nymphs swarmed into cultivated fields from surrounding grass 

 ands where they went through the first part of their develop- 

 ment. The drought forced greater numbers to migrate to irri- 

 gated crops and must as well have been very favorable to the 

 production of the species. Potatoes and gardens suffered the 

 most. Corn seemed to recover from what at first appeared to 

 be rather serious injury. 



