12 MONTANA EXPERIMENT STATION BULLETIN 504 



PEA APHID (Macrosiphum pisi) 



Only light infestations of pea aphids on alfalfa occurred in 1953; how- 

 ever, there appeared to be quite a large buildup in 1954 in most of the 

 alfalfa areas. In most cases, the control measures recommended for lygus 

 bugs took care of the aphids. WTiere alfalfa was used for forage, this insect 

 was virtually eliminated when the hay was cut. 



POTATOES 



COLORADO POTATO BEETLE (Leptinotarsa decemlineata) 



Local infestations occmTed in Dawson, Lewis and Clark, Sweet Grass, 

 and Ravalli counties in 1953. Gallatin, Madison, and Lewis and Clark 

 counties had higher than usu.al populations dvning 1954. This beetle is 

 readily controlled wnth DDT. The gt-neral recommended practice has been 

 to apply this insecticide in 100 gallons of water per acre. At the present 

 time there appear to be indications that good control may be achieved with 

 as little as 25 gallons of water per acre, provided conscientious and eff'- 

 cient methods of application are used. 



POTATO PSYLLID (ParatHoza cockerelli) 



Several moderate infestations occurred on potatoes in Carbon County 

 in 1953. There was little activity and no infestation reported during 1954. 



FLEA BEETLE (Epitrix sp.) 



These insects were present on potatoes in economic proportions in 

 Gallatin Countv' in 1953. They were present in Gallatin, Madison, Park, 

 Fergus, and Lewis and Clark counties in higher than nonual populations 

 in 1954. Either toxaphene or DDT controls this insect. 



SUGAR BEETS 



BEET WEBWORM (Loxostege sticticalis) 



Severe infestations occurred on sugar beets in Custer, Rosebud, Treas- 

 ure, Big Horn, Yellowstone, Carbon, Broadwater, Richland, and Roosevelt 

 counties during the biennium. Three local infestations in alfalfa were 

 reported along the Yellowstone River in 1954. In Gallatin County in 1953 

 these insects invaded seed and canning peas and produced a considerable 

 amount of damage. 



BLACK CUTWORM (Agrotis ypsilon) 



Severe damage occurred in many sugar beet fields in Big Horn County. 

 The damage was primarily caused from subterranean girdling of plants in 

 the crown area after which most of the damaged plants would die. There 

 were no economic infestations reported during 1954. 



