MONTANA INSECT PESTS, 1953-1954 .11 



ALFALFA AND CLOVER 



ALFALFA WEEVIL (Hypera postica) 



This pest of alfalfa is occurring over an ever-widening range in Montana. 

 Almost all the counties in the state, except those north of Deer Lodge and 

 Silver Bow counties in the western part of the state, have infestations of 

 this insect. At the present time this pest has reached the northern border 

 of Montana on approximately a 300-mile front and has penetrated about 

 80 miles into Canada. Since Montana has worked out an efficient method 

 of combatting this pest, the Provincial governments of Alberta and Sas- 

 katchewan have requested assistance from this office in initiating a control 

 program in those areas. Technical assistance, in the form of advice and 

 in the loan of instructional aids, has been given. At the present time, the 

 best method of control is in the use of heptachlor or dieldrin applied at 

 the rate of ¥4 pound of the active ingredient per acre. 



LESSER CLOVER LEAF WEEVIL (Hypera nigrirostris) 



Several damaging infestations were reported in Lake Count\', and one 

 field of ladino ckn'er in Ravalli County was seriously damaged by this 

 insect. Although this weevil appears to be present on almost all clover 

 plants in the state, it apparently reaches economic proportions only in widely 

 scattered areas. 



LYGUS BUG (Lygus spp.) 



The incidence of Lygus bugs has been rather high during the last 

 biennium, especially during mid- and late summer. Some control measures, 

 using toxaphene. have been necessary over widely scattered areas of the 

 state where alfalfa seed is produced. Treatment for these insects is made 

 after 7 o'clock in the evening or before 7 o'clock in the morning to protect 

 the valuable pollinators— the honey bees and the alkali bees. 



SWEETCLOVER WEEVIL (Sitona cylindncollis) 



The damage by this insect was confined largely to the western part 

 of the state. Some marginal defoliation of alfalfa occurred over widely 

 scattered areas. 



VARIEGATED CUTWORM (Peridroma margaritosa) 



In 1953 light to moderate infestations occurred in alfalfa fields in 

 Prairie and Rosebud counties. No economic infestations were reported 

 during 1954. 



ALFALFA SEED CHALCID {Bruchophagus gibbus) 



Although no extremely severe infestations of this insect were known 

 to exist during the biennium, very light and widely scattered infestations 

 occurred over most of the alfalfa-seed-producing areas in the state. Trash 

 removal and crop rotation on a community wide basis are the best weapons 

 we have against this insect. 



