16 MONTANA EXPERIMENT STATION BULLETIN 526 



CICADA (Homoptera: Cicadidae) 



Cottonwood trees were damaged in Pondera County by these 

 insects during 1955. 



COTTONY MAPLE SCALE (Pulvinaria innumerabilis) 



This insect appears to be on the decline. Two infestations from 

 Chouteau and Flathead counties were reported in 1955. None was 

 noted in 1956. 



COTTONWOOD LEAF BEETLE (Chrysomela scripta) 



Many of the poplar and cottonwood insects appear to be building 

 ap in the state. There are many new plantings of these and other 

 tree varieties being used for shelterbelts, and farmers and ranchers 

 are becoming more aware of insect damage since they have a con- 

 siderable investment involved. 



In 1955 the cottonwood leaf beetle was reported damaging cotton- 

 woods in Valley County. It did damage in Chouteau and Glacier 

 counties on cottonwoods in 1956. 



A COTTONWOOD LEAF MINER (Lepidoptera: Tischeriidae) 



This insect was very abundant in the northern tier of counties 

 during 1956. It is believed to be of little economic importance but 

 it renders trees unsightly because of the dark leaf splotches. 



COTTONWOOD LEAF-STEM GALL (Pemphigus populi-transversus) 



This aphid was generally distributed over much of the central 

 part of the state in 1955. In 1956 occasional light infestations were 

 noted in the same area but the population appeared to be declining. 



COTTONWOOD STEM GALL MITES (Eriophyes sp.j 



During 1955 infestations were recorded for Glacier, Blaine, and 

 Prairie counties. One infestation from Richland County was reported 

 in 1956. 



ELM LEAF APHIDS (Myzocallis ulmifolii) 



A continuance of the 1954 general infestation persisted through 

 1955. Almost all extensive elm plantings in the state showed evidence 

 of damage by this insect. During 1956 only residue populations 

 appeared to be present in widely scattered spots. 



