MONTANA INSECT PESTS, 1949 AND 1950 23 



INSECTS DESTRUCTIVE OF FRUIT CROPS 



ORCHARDS 



BLACK CHERRY FRUIT FLY (Rhagoletis fausta) 



In the Thirty-Second Report of the State Entomologist the 

 black cherry fruit lly was erroneously reported as Rhagoletis 

 cingulata. The only known fruit fly of cherries in Montana is the 

 black cherry fruit fly Rhagoletis jausta. A severe outbreak of this 

 insect, the larvae of which burrows into the cherries, occurred 

 in the southern end of the sweet cherry belt on the east shore 

 of Flathead Lake in 1949. A survey was initiated in 1950, and 

 adult cherry fruit flies were found in 35 out of the 210 orchards 

 in the East Shore area. One dusting of 15% lead arsenate and two 

 dustings of % of 1% rotenone has satisfactorily controlled this 

 insect. 



RUST MITES (Phyllocoptes sp.) 



Populations of rust mites in the sweet and sour cherry trees 

 of western Montana were below economic levels in 1949 and 1950. 



EUROPEAN RED MITES (Paratetranychus pilosus) 



European red mites have been known to be present in western 

 Montana since 1947, when they were found in the Poison area. 

 These infestations apparently have not spread to any great extent 

 since they were first noted. They are of economic importance in 

 this area on cherries and apples. 



PEAR SLUG (Caliroa cerasi) 



Several stone fruits are usually subject to attack by the pear 

 slug in Montana. In the past two years they have been reported 

 or found only on sour and sweet cherries and populations were 

 low, but they were of economic importance. Pear slugs are readily 

 controlled by a pre-harvest application of rotenone, or a post- 

 harvest application of toxaphene. 



BLACK CHERRY APHID (Myzus cerasi) 



Black cherry aphids are commonly found wherever sweet 

 cherries are grown in Montana. In general, populations were high- 

 er in 1949 than in 1950. In both years black cherry aphids were of 

 economic importance in sweet cherries. Dinitro dormant sprays 

 or toxaphene or tetraethyl pyrophosphate as green tip sprays have 

 effective^ controlled this insect. 



CODLING MOTH (Carpocapsa pomonella) 



Codling moths are found everywhere in Montana where apples 

 are grown. Control measures normally undertaken in commercial 

 orchards usually keep this pest below the level of economic im- 

 portance. The only cases of severe damage to apples by codling 



