TWENTY-NINTH REPORT OF THE STATE ENTOMOLOGIST 11 



should recognize these problems and help to reduce their impor- 

 tance as far as it is humanly possible to do so. 



MORMON CRICKET CONTROL, 1941-42 

 O. B. Hitchcock, Assistant State Entomologist 



During the last two years the Mormon cricket infestation 

 throughout the State has decreased to such an extent that it is no 

 longer the major insect problem that it was. 



In 1941 there were five counties with cricket populations high 

 enough to make control measures necessary. These infestations 

 were in Beaverhead County west of Monida near the Montana- 

 Idaho line; Big Horn County east of Lodge Grass and Owl Creek 

 and Sioux Pass, and southwest of Hardin in the vicinity of Beau- 

 vais Creek; near Pry or; Chouteau County in a large area including 

 Highwood, Geraldine, Square Butte, and Montague; Sanders 

 County in Fairy Basin, McDonald Basin and in the hills east of 

 Camas Prairie; and in Yellowstone County along Pry or Creek, Hay 

 Creek, Blue Creek, Fly Creek and surrounding area. 



The infested areas in Beaverhead and Sanders counties were 

 relatively small and after the control work was completed only a 

 few scattered crickets could be found, with exception of the high 

 areas in Beaverhead County, where heavy populations occurred. 

 The populations in other infested areas were not so heavy as in 

 previous years but were quite extensive and control work was 

 done on a crop-protection basis. Because of the control program 

 very little crop damage occurred. 



Until 1939 the use of bait was not recommended as an effective 

 method of controlling Mormon crickets; however, the use of sodium 

 fluosilicate as the active agent instead of sodium arsenite was 

 proved successful, and since 1939 the amount of bait used has in- 

 creased steadily until this year when its use almost entirely re- 

 placed the use of sodium arsenite dust. The bait has many ad- 

 vantages over the dust in that it is more effective, easier and less 

 dangerous to handle, cheaper, and the hazard of livestock poisoning 

 is greatly decreased. The first hatching of Mormon cricket eggs in 

 1941 was reported in Big Horn County on March 31. The main 

 hatch over the State, however, did not occur until about the 15th of 

 April. 



In Yellowstone County a few eggs were found to be parasitized 

 by Sparaison pilosum Ashm. The predatory wasp Palomedes laevi- 

 ventris Cress, was observed in most of the infested areas but was 

 not numerous enough to be important in reducing the population 

 of Mormon crickets. 



No extensive migrations were observed. However, there was 

 some movement of small bands of crickets out of the Wolf Moun- 



