MONTANA INSECT PESTS, 1953-1954 7 



ARMY CUTWORMS (Chorizagrotm auxiliaris) 



Army cutworms showed an average infestation in 1953. Scattered, 

 light to moderate damage occurred in Chouteau, Sheridan, and Roosevelt 

 counties. A ven,' light uneconomic infestation occurred in Stillwater County. 

 In 1954 damage occurred over a much wider area and was more severe 

 in general. Cascade, Chouteau, Fergus, Musselshell, Golden Valley, Still- 

 water, and Yellowstone counties suffered spotted severe damage, especially 

 in winter wheat. In addition, Wibaux, Fallon, Carter, Big Horn, Carbon, 

 Gallatin, Jefferson, Madison, and Broadwater counties had moderate local 

 infestations. Because of the inclement weather existing throughout the 

 infestation period which occin-s from February to May, toxaphene, which 

 has been the recommended control spray, has shown erratic results. Con- 

 sequently, endrin, at the rate of one ounce per acre, was used and gave 

 excellent results. 



WIREWORMS AND FALSE WIREWORMS 

 (Families: Elatcridac 8 Tcncbrionidac) 



Wireworm damage, during the biennium, was general throughout the 

 state, especially in the regions where wheat and root crops are grown. 

 The general areas of infestation in 1953 were in the northeast comer of 

 the state, in the north-central part of the state, in the southwestern part 

 of the state, and in the northwestern part of the state. In 1954 the areas 

 were approximately the same except that the central part of the state ex- 

 perienced more damage than usual. Seed treatment, with one ounce of 

 lindane per bushel of seed, will eliminate these pests. There is, at the 

 present time, a change-over being made in many of the seed-treating machines 

 throughout the state which enables simultaneous treatment with a solution 

 of aldrin for wireworm control and organic mercury for fungus control. 



ARMY WORMS (Pseudaletm unipuncta) 



For the first time since 1937 an arm\' worm outbreak occurred in Mon- 

 tana. Generally, this outbreak followed the Yellowstone River Valley from 

 Billings east to the North Dakota border. Infestation in small grains oc- 

 curred in Big Horn, Rosebud, and Prairie counties. In addition, infestations 

 in sugar beets occurred in Big Horn Count>' and in alfalfa in Rosebud 

 County. In Richland County the army worms were found to be attacking 

 sweet com. These pests were controlled quite readily with 3/10 of a 

 poimd of endrin per acre. In one case where residues were a factor, para- 

 thion was used with good results. 



PALE WESTERN CUTWORMS (Agrotis orthogonia) 



No serious infestations of pale western cutworms were reported in 

 1953. In 1954 moderate infestations occurred in Hill and Musselshell 

 counties. 



