MONTANA INSECT PESTS, 1951-1952 19 



SPRING CANKERWORM (Paleacrita vernata) 

 Localized outbreaks of this pest occurred in central Carbon 

 County, southern Rosebud County, and southeastern Valley 

 County in 1951. These outbreaks were largely confined to native 

 trees on creek bottoms and few control measures were initiated. 

 An infestation was reported in Chouteau County in 1952. 



A TENT CATERPILLAR (Malacosoma sp.) 



Only one infestation of tent caterpillars (at Bozeman) was re- 

 ported in 1951. In 1952, light to moderate infestations occurred 

 over much of western and southcentral Montana with the prin- 

 cipal damage being to apple trees and roses. A DDT spray pro- 

 vided excellent control. 



COTTONY MAPLE SCALE (Pulvinaria vitis) 

 Only a single infestation of this pest was reported during the 

 biennium. This occurred in 1952 in Lincoln County. 



OYSTERSHELL SCALE (Lepidosaphes ulmi) 

 Oystershell scale is commonly present in most unsprayed 

 orchards and on back yard fruit trees. In 1952 it was found to be ex- 

 tremely prevalent on Cotoneaster shrubs in most of western and 

 parts of eastern Montana. This scale can be controlled with dor- 

 mant sprays. 



BIRCH SKELETONIZER (Bucculatrix canadensisella) 

 A moderate to severe outbreak of birch skeletonizer occurred 

 in Lewis and Clark County in 1951. This chewing lepedopterous 

 pest of birch trees was not reported or observed in 1952. 



COTTONWOOD-LEAF MINER (Proleucoptera albella) 

 This insect pest probably occurs throughout the entire state 

 along with cotton wood trees. Several cases of severe damage have 

 been reported from the northcentral section of the state during 

 both years of the biennium. This pest is frequently heavily para- 

 sitized so that extensive damage is not expected to be re-occurrent 

 for long periods of time. No practical control measures are known 

 at present. 



A LEAF ROLLER (Archips sp.) 

 A tree leaf roller was found and reported to be causing ex- 

 tensive damage to Russian olives, caragana, and apples in north- 

 central and northwestern Montana during June of 1952. This is 

 the only occurrence of this insect reported during the biennium. 



CARPENTER WORM (Prionoxystus robiniae) 

 Only a single infestation of these borers of living trees was 

 reported during the biennium. This occurred in 1951 in Broad- 

 water County. 



