12 MONTAJVA EXPERIMENT STATION BULLETIN 442 



A small area was dusted with 5 per cent DDT dust in an effort 

 to determine the effect of this insecticide upon crickets. Excellent 

 results were obtained, and good kills also were observed on an ad- 

 jacent area covered by dust drifting from the test plot. The driftmg 

 dust was effective for a distance of over 200 yards. 



EARWIGS (Forficula auricularia) . — Since earwigs were first 

 reported in Sanders County in 1939', the infestation has gradually 

 spread to other counties and the economic importance of these in- 

 sects as garden pests and household nuisances has greatly increased. 

 In 1945 and 1946, they were reported doing considerable damage 

 to gardens and truck crops in Sanders, Lake, and Flathead coun- 

 ties. In 1946 the most severe infestation of earwigs ever to occur 

 in the State was recorded in Flathead County in the vicinity of 

 Columbia Falls. The damage caused by the insects to gardens in 

 this area was quite extensive. 



ALFALFA WEEVIL (Hyperia postica) . — The alfalfa weevil, 

 which has been discussed in previous reports*, was abundant and 

 highly injurious to alfalfa in its area of infestation during both 

 years of the past biennium. This represents the first evident injury 

 from this pest in the State. 



On July 6, 1945, a survey was made of the western part of the 

 area. The alfalfa weevil was found to be abundant and injurious 

 near Silesia, with the first cutting of hay reduced by 50 per cent in 

 some spots. This weevil was also abundant at Joliet and consider- 

 able damage was evident. Light injury was apparent on the Carbon- 

 Stillwater county line between Boyd and Columbus, and five miles 

 southeast of Columbus moderate numbers and some damage were 

 observed. The westernmost larvae were swept from an alfalfa field 

 one-half mile west of the viaduct on Highway No. 10 between 

 Columbus and Reed Point. Other observations and reports indicat- 

 ed that the alfalfa Vv^eevil was present throughout Carbon, southern 

 Yellowstone, southern Treasure, Big Horn, southern Rosebud, and 

 into Powder River counties, and injury was substantial through 

 the central part of this area. 



In 1946 Montana experienced its most severe alfalfa weevil 

 outbreak. Extremely heavy infestations of this insect occurred in 

 Csrbon. Stillwater, Yellowstone, Big Horn, Treasure, Rosebud, 

 Powder River, and Custer counties, and the hay and alfalfa seed 

 crop in these counties was severely damaged by this insect. Since 

 the alfalfa weevil is comparatively new to most of the area, many 

 farmers were not aware of its presence. They blamed weather 



»Mont. Agr. Exp. Sta. Bull. 384, p. 25. 



*Mont. Agr. Exp. Sta. Bulls. 384, p. 23, 1941, and 425, pp. 21-22, 1945. 



