10 MONTANA EXPERIMENT STATION BULLETIN 526 



stand over a foot high, even though the wheat was mature. Cultural 

 control methods are the only effective weapons we have against this 

 insect at the present time. 



WHEAT STEM SAWFLY (Cephus ductus) 



The wheat stem sawfly continues to expand its economic range in 

 Montana and severe infestations were present in McCone and neigh- 

 boring counties in 1955. These locations are outside the usual area 

 of damage from this insect. In 1956 economic damage was discovered as 

 far west and south as Sweet Grass County. 



WHEAT-HEAD ARMY WORM (Protoleucania albilinia) 



The wheat-head army worm attacks the ripening heads of wheat. 

 Local infestations were reported in Liberty, Toole, and Hill counties 

 in 1955. Local mild infestations occurred in Chouteau County in 1956. 



WESTERN WHEAT APHID (Brachycolus tritici) 



Hill, Valley, and Yellowstone counties reported this pest in 1955. 

 No infestations were reported in 1956. 



PALE WESTERN CUTWORM (Agrotis orthogonia) 



For the first time in a number of years, the pale western cutworm 

 was a major pest of wheat. In 1955 infestations occurred in Yellow- 

 stone, Madison, Gallatin, and Pondera counties. Although these in- 

 festations were not of great intensity, they were apparently capable 

 of building up populations for 1956 since rather severe outbreaks 

 occurred in Chouteau, Broadwater, Jefferson, Yellowstone, Pondera, 

 Teton, and Cascade counties. Until the last 2 years the only method 

 of control for this insect has been through cultural practices. Recent 

 evidence indicates that by using one of the new chlorinated hydro- 

 carbons known as endrin control of this pest may be possible with 

 chemicals. 



Corn Insects 



EUROPEAN CORN BORER (Pyrausta nubilalis) 



Although this pest is present only in the lower Yellowstone Valley, 

 it offers a rather serious deterrent to corn production in this area. 

 Most of the highly effective chemical control methods require special- 

 ized equipment which cannot be economically used on the small corn 

 acreage in this state. However, cultural control with some help from 

 chemicals enables farmers to keep losses from this pest at a minimum. 



