10 MONTANA EXPERIMENT STATION BULLETIN 484 



in most of the other major wheat growing counties east of the 

 Continental Divide. An estimation of losses was prepared by the 

 Bureau of Entomology and Plant Quarantine of the United States 

 Department of Agriculture. According to this estimate, a loss of 

 approximately 1,422,751 bushels of wheat was attributed to the 

 wheat stem sawfly in Montana during this season. 



At the time of this writing, the 1952 sawfly survey was not 

 completed. However, it does appear that in general the sawfly in- 

 festation was similar to that of 1951. 



WHEAT STEM MAGGOT (Meromyza americana) 



Scattered infestations of wheat stem maggots occurred in 

 Fallon, Wibaux, Prairie, Dawson, McCone, Richland, Daniels, and 

 Lake counties in 1951 and in Sweetgrass, Stillwater, Phillips, 

 Toole, Daniels, Sheridan, Richland, McCone, Dawson, Wibaux, 

 and Custer counties in 1952. In all cases less than 5 percent of the 

 plants were infested with average infestations of from 1 to 2 per- 

 cent. 



WHEAT JOINTWORM (Harmolita tritici) 



A few scattered light infestations of wheat jointworm oc- 

 curred in Yellowstone and Stillwater counties in 1951. In 1952 the 

 wheat jointworm was more prevalent in northern Sweetgrass 

 and Stillwater counties where it inflicted severe damage. This 

 jointworm also occurred in Phillips and Daniels counties in 1952. 

 In the event that damage of the type that occurred in northern 

 Sweetgrass and Stillwater counties in 1952 should become more 

 widespread, this insect could become one of the leading pests of 

 wheat. 



GRAIN THRIPS (Limothrips cerealium) 



Spotted moderate to severe infestations of grain thrips in 

 oats occurred in Stillwater County in 1951. This is the only out- 

 break reported or observed during the biennium. 



A WHEAT HEAD ARMYWORM (Faronta sp.) 

 Numerous infestations of a wheat head armyworm occurred 

 in Chouteau, Cascade, and Fergus counties, during late July and 

 early August of 1952. In most cases the worm was not observed 

 until found in the harvested wheat. This insect was feeding on the 

 mature, or nearly mature, wheat kernels. In all cases observed, 

 the insects were not prevalent enough to cause damage of eco- 

 nomic importance. This insect was not reported or observed during 

 1951. 



A WHEAT LEAF SAWFLY (Tenthredinidae family) 

 Extensive infestations of a wheat leaf sawfly were found in 



