MONTANA INSECT PESTS, 1955-1956 15 



SPIDER MITES (Acarina: several species) 



During 1955 only a few infestations in the south central part of 

 the state were noted. In 1956, due at least in part to the dry weather, 

 very high populations of this insect ranging over all areas of the state 

 were present on raspberries, apple, currant, and ornamental fruit trees. 

 Spider mites are not hard to control with organic phosphates, sulphur, 

 or even water, but because of their minute size damage is often well 

 advanced before it is noticed. 



RASPBERRY CANE BORER, CANE MAGGOT, AND ROOT BORER 

 (Oberea bimaculata, Pegomya rubivora, and Bembecia marginata) 



Since drenches of aldrin and pruning of infested stems have been 

 practiced, very few infestations of these insects have been reported 

 in the state. 



CURRANT FRUIT FLY (Epochra canadensis) 



Currant fruit fly continues to be a bad pest of currants and 

 gooseberries in the central and southern parts of the state where pre- 

 ventative control measures are not practiced. 



CURRANT APIIIDS (CapUophorus ribis) 



No infestations were reported in 1955. Damage occurred in 

 Sanders and Stillwater counties in 1956. 



INSECTS DESTRUCTIVE TO ORNAMENTAL PLANTS 

 Deciduous Ornamentals 



ASH PLANT BUG (Neoboms amoenus) 



The general trend in numbers of this insect has been downward 

 during this biennium. However, moderate infestations continued 

 to exist in central and north central Montana during 1955. Light to 

 moderate infestations were spotted throughout this same general area 

 in 1956. 



A BOX ELDER GALL (Diptera: Cecidomyiidae) 



A rather severe infestation of this insect occurred in Billings during 

 1956. No apparent economic damage resulted. 



CARPENTER WORM (Prionoxystus robiniae) 



One infestation of this wood-boring insect was reported from 

 McCone County in ash trees in 1956. 



