10 MONTANA EXPERIMENT STATION BULLETIN 384 



gardless of State lines, and preparations for campaigns may have to 

 be made on such an area basis rather than on a county basis. 



Mormon Cricket Control 1939-1940 



The period of 1931-1938 marked the most extensive Mormon 

 cricket invasion of crop areas ever recorded in the State. The 

 seriousness of the situation has greatly decreased in the last two 

 years. During 1938 the infestation reached its peak, with an estimat- 

 ed 2,209,078 crop acres and 5,542,407 range acres infested. Most of 

 these 7,751,485 acres were quite thickly populated with crickets. In 

 1939 there was a decrease of approximately 74 per cent in infested 

 cropland and 43 per cent on the range. In 1940 still another de- 

 crease was noted; infested crop areas were reduced 69 per cent and 

 range 38 per cent. Comparison of the peak infestation of 1938 with 

 the condition at the end of the 1940 campaign indicated a two-year 

 reduction of 78 per cent on cropland and 84 per cent on the range, 

 giving a total reduction for all infested acres of 81 per cent (table 3) . 



TABLE 3.— DECREASE IN MORMON CRICKET INFESTATION 1938 TO 1940 



1938 to 1939 1939 to 1940 1938 to 1940 



Average Average Average 



decrease % decrease % decrease % 



acres decrease acres decrease acres decrease 



Crop 1,626,258 74 218,800 69 1J3457058 78 



Range 1,715,007 31 2,628,300 38 4,343,307 84 



Total ... 3,341,265 43 2,847,100 65 6,188,365 81 



Several factors probably are responsble for this decrease in in- 

 festation. It is apparent that control work is responsible for a good 

 deal of the reduction. Besides the destruction of tremendous num- 

 bers of crickets by the use of dust, bait, and oil and metal barriers, 

 there are indications that when the crickets are disturbed a large 

 number of the eggs which they lay will not hatch. Climatic condi- 

 tions in all likelihood play an important part, although it is not 

 known what conditions affect the crickets adversely. In past years 

 parasites and predators have been important agents in reducing 

 populations of crickets. In most areas in the State the egg para- 

 site, Sparaison pilosum Ashm., has been noted in increasing num- 

 bers for several years, and large numbers of parasitized eggs have 

 been collected. The sphecid predator, Palmodes laeviventris Cress., 

 has been increasing in numbers, and was very abundant in certain 

 areas in 1940. Field mice habitually dig out the eggs and eat them. 

 In one area where the eggs were concentrated the mice had de- 

 stroyed 43 per cent of the eggs. When crickets are available, various 

 species of birds feed extensively on them. As many as 53 hawks 

 (probably Swainson's and the red tail) have been seen preying on a 

 single band in Beaverhead County. An examination of regurgitated 

 hawk pellets disclosed a large number of cricket legs, and other 

 indigestible heavily sclerotized parts. Other birds which were no- 



