Montana Stale Library 



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MONTANA INSECT PESTS 

 1947 and 1948 



THIRTY-SECOND REPORT OF THE STATE ENTOMOLOGIST 



J. H. Pepper, O. B. Hitchcock, C. R. Hunt, 



Ralph Schmiedeskamp^ 



INTRODUCTION 



The entomological outlook for Montana presents a number of 

 ramifications which have not been previously stressed. Our insect 

 problems have increased in the last decade and the possibility of 

 further serious situations arising is almost certain. 



During the last few years, we have had infestations of a number 

 of insects new to the state. Likewise, some native insects that have 

 not previously been pests have caused considerable damage to 

 agricultural crops. It had been predicted by earlier workers that 

 two of these new insects, the alfalfa weevil and the differential 

 grasshopper, could not become established in Montana because of 

 our ecological conditions. At the present time both of these insects 

 have become serious pests. The differential grasshopper was first 

 found in Dawson County in 1932. Since that time it has spread over 

 much of the eastern and southern parts of Montana and is now 

 found in economically important numbers as far west as Yellow- 

 stone and Big Horn counties. The alfalfa weevil was first observed 

 in 1938 and has been a serious pest to alfalfa in Southeastern 

 Montana since 1945. It has spread every year and at the present 

 time it is as far north and east as Terry and as far west as Reed 

 Point. This pest has become so serious in some sections that it has 

 threatened the alfalfa seed and feed growing industries. 



It was assumed by many of the early workers that climatic 

 factors were primarily responsible for limiting the distribution of 

 many of these pests. It is apparent from the above examples that 

 the ability of an insect to adapt itself cannot be overlooked in 

 predicting the limits of its geographic distribution. 



The wheat stem sawfly, which is a native insect of Montana, 

 did not become important economically until 1941. Since that time 

 this insect has become one of our most serious pests of spring and 

 winter wheat, at present confining itself largely to the northern 

 part of the state. 



Changes in our agricultural crops and farm practices have 

 resulted in bringing about conditions which are more favorable to 

 some insects. It is interesting to note that the spread of the wheat 



iState Entomologist, Assistant State Entomologist, Montana Agricultural Experiment 

 Station Entomologist, Assistant State Apiarist, respectively. 



