

THIRTIETH REPORT OF THE STATE ENTOMOLOGIST 21 



1943. This infestation was believed to have resulted from infested 

 seed, which was not fumigated before planting. All seed planted 

 in 1944 was weevil-free, and apparently the 1943 infestation died 

 out. There are few suitable hibernation places in the Flathead 

 Valley and this perhaps accounts for the elimination of the infesta- 

 tion. 



Southwest of Missoula moderate to heavy infestations were 

 encountered. Infestations of 2.3, 2, 14.5, and 5.8 weevils per 100 

 sweeps were recorded. Since all seed planted in this area was 

 weevil-free, it is apparent that successful hibernation has occurred 

 Harvest data are not available for these fields but it is known that 

 the third field was abandoned. In the infested area there are 

 plenty of adequate hibernation places available. Continued in- 

 crease in weevil populations may seriously affect the growing of 

 seed peas in the Missoula area. 



alfalfa weevil (Hyper a postica Gyll.) . — Records of the oc- 

 currence of this insect in the State have been briefly reviewed 

 previously 5 and will not be repeated here. An additional record 

 representing a slight extension of the range has been obtained 

 since that time. On June 16, 1943, Mr. R. H. Newton of the United 

 States Bureau of Entomology and Plant Quarantine obtained a 

 few larvae in an alfalfa field located near where the Billings- 

 Hardin highway crosses Pryor Creek in southern Yellowstone 

 County. These larvae were retained alive in a vial by Mr. New- 

 ton, and the parasite Bathyplectes curculionis Thorn., was reared 

 from them. As there have been no liberations of these parasites 

 in the State it is apparent that the weevils have brought the para- 

 sites in with them as they have progressed north from the Wyom- 

 ing boundary. 



The area infested with the alfalfa weevil in Montana is ap- 

 parently small and restricted, and the infestations to date have 

 been light. In this connection it is interesting to refer to a paper 

 by Cook" published nearly 20 years ago, in which the probable 

 distribution of the alfalfa weevil is outlined. Cook divided the 

 western United States into three types of areas related to the 

 probable success of this invading pest. The first is the area of 

 normal occurrence where severe infestations may occur, and 

 second is an area of occasional occurrence where periodic infesta- 

 tions depending on climatic fluctuations may occur, and the third 

 is an area of possible occurrence where the weevil might become 

 of minor economic importance after a series of favorable years. 

 There are no areas noted in Montana where severe infestations 

 may occur. The second degree of infestation, occasional occurrence, 

 may appear west of the Divide and north about to Flathead and 



sMont Agr. Exp. Sta. Bull. 384, p. 23, 1941. 

 "Jr. Agr. Res. 30, pp. 479-491, 1925, 



