22 



BULLETIN 1103, U. S. DEPARTMENT OF AGRICULTURE. 



alfalfa weevil caused little injury this season; although climatic 

 conditions may explain part of this phenomenon, it is evident that 

 the parasite BatJiyylectes curculionis Thoms. has been an important 

 factor. 



In Payette County the beetles were so numerous as absolutely to 

 prevent any growth of the second crop for from four to six weeks, 

 and in many places they turned their attention to garden truck after 

 completely defoliating the alfalfa. 



In Wyoming the weevil has been found in the southern part of 

 Lincoln County, at several points in Uinta County, and at two points 

 in Sweetwater County in the southwestern corner of the State. 



Fig. 9. — Geographical distribution of the alfalfa weevil in the United States in 1921 : 

 Shaded areas, generally infested ; black dots, definite infested localities. 



To the west, the Utah infestation has extended into Nevada, in the 

 eastern third of White Pine County, and to the northwest this in- 

 festation has extended through Idaho into the northern part of 

 Malheur County, Oreg. 



Isolated outbreaks, probably the result of commercial transporta- 

 tion, have been discovered near the California State line in southern 

 Washoe County, Nev., and in the east-central part of Colorado, in 

 Delta, Montrose, and Gunnison Counties. 



The weather conditions over the region infested by the alfalfa 

 weevil show no excessive departures from the normal. The tempera- 

 ture during the fall of 1920 was slightly below normal, while the 

 winter of 1920-21 was characteristically mild, the temperatures rang- 

 ing between 3° and 4° F. above normal. April was generally cold, 



