116 
PRELIMINARY LIST 
Fort Collins, July 12th, on Populus monilifera, forming a 
pseudo gall by causing the upper surfaces of the leaf to fold 
together along the midriW Coven). 
Pemphigus popali-monilis Riley and Monell. 
In Colorado, on narrow leaved cottonwood (Riley and Monell, 1). 
Fort Collins, July 17th, in typical moniliform galls on 
leaves of Populus angustifolia; Hotchkiss, Delta County, 
July 14th, on the same host plant. Only one individual was 
found in each gall (Cowen). 
Pemphigus populi-ramulorum Riley and Monell. 
On Populus balsamifera, Colorado (Riley—see Riley and Monell, 1). 
Fort Collins, July 12tli, on Populus monilifera, in galls at 
base of petiole and on twigs. Sometimes the galls of this 
species are far enough up the petiole to be almost distinct 
from the twig, and are then quite similar to those of P. 
populi-transversus (Cowen). 
Pemphigus populi-transversus Riley and Monell. 
On Populus monilifera and P. balsamifera, Colorado (Riley—see Riley and 
and Monell, 1). 
Fort Collins, July 12tli, in typical galls with transverse 
openings, on petioles of Populus monilifera (Cowen). 
Pemphigus vagabundus W alsh. 
Fort Collins, galls on Populus (Blinn). 
Colopha ulmicola Fitch. 
Fort Collins, July 8th, in “cockscomb'’ galls on Plmus 
americana. Five of the specimens examined have the 
cubital vein of fore wings simple (Cowen). 
Schizoneura americana Riley. 
Fort Collins, June 17th, on IJlmus americana (Cowen). 
Schizoneura lanigera Hausm. 
Boulder, Denver, Canon City, Delta, and Grand Junction, 
on apple, common (Gillette). Hotchkiss, Delta County, 
August 23d, on young shoots of crab-apple (Cowen). 
Scliizonenra querci Fitch. 
“Wingless form: Largest a little over 1 mm. long, very wooly, uniformly pale green, 
except eyes which are red, and black tip of beak. Beak reaching slightly beyond second 
