Sept. 23,1918 
Pemphigus populi-transversus 
59i 
each 0.55 mm.; body and legs very free from hairs; apparently no wax glands on the 
body (PI. 81, E, I). 
Pupa. —Almost uniform pale lemon yellow with slight greenish tinge on abdomen 
and a shade of flesh color upon the thorax; wing pads very slightly dusky along the 
outer margins; head, antennae, and all the legs dusky; eyes black. 
Winged sExupara. —Described from living specimens taken by Mr. 
T. H. Jones, Baton Rouge, La., on March 21, 1917, bred from Brussels 
sprouts, and from preserved specimens from Mr. F. B. Paddock, College 
Station, Tex., which were taken on February 2, 1913; from Mr. E. S. 
Tucker, Baton Rouge, La., taken on March 5, 1915, on turnips; and 
from one specimen taken by Mr. L. C. Bragg, near Fort Collins, Colo., 
on watercress (Roripa sp.) on August 31, 1917. 
Head, antenna, entire thorax above, mesothorax below, and entire legs black; 
wings slightly smoky, with subcostal vein black or blackish and heavy along the 
inner or lower margin of the stigma; abdomen sordid light greenish yellow without 
markings; body everywhere with a slight covering of gray powder; dorsum of abdomen 
covered more or less with a cottony secretion; length of body 2 mm.; wing 2.70 mm.; 
antenna 0.60 mm.; hind tibia 0.75 mm.; joints of antenna in following proportions: 
1, 22; 2, 30; 3, 65; 4, 32; 5, 32; 6 with spur, 56; sensoria transverse, joint 3 with four 
to eight, usually five or six; 4 with two or three; 5 and 6, normally, with permanent 
sensoria only; spur near base of joint 3 distinct. Permanent sensorium on joint 5 
usually very large, often inclosing one or two chitinous pieces as in fundatrigene. 
Nervures of wing dusky, the costal and subcostal being heavy and black; stigma 
blackish, nearly parallel sided, and about three times as long as broad (PL 81, D, K). 
Oviparous female. —Described from a number of specimens de¬ 
posited in a cage in the laboratory by specimens sent by Mr. T. H. Jones, 
from Baton Rouge, La. 
General color buttercup yellow, with head, antennae, and legs whitish and very 
transparent; a little dusky on the vertex; eyes black; antennae short, 0.15 mm. long, 
4-jointed, joints subequal, the first, and last including the spur, longest; length of 
body 0.70 to 0.90 mm. (PI. 81, G). 
Egg. —Oblong oval, glistening, varying in color from dull white to yellow. Ten 
eggs, deposited in the laboratory, averaged 0.54 mm. in length, ranging from 0.48 to 0.57 
mm., and 0.21 mm. in width, ranging from 0.19 to 0.24 mm. 
Male. —Described from specimens born along with the oviparous 
females. 
The males differ from the females by being pale yellowish green in color, more slen¬ 
der in form, and a little shorter, 0.60 to 0.65 mm, long, the legs very stout (PI. 81, F). 
Galls. —Riley described the gall of this species as follows: 
Formed upon the petiole near the base of the leaf of Populus monilifera and P. 
balsamifera. An elongate-oval swelling, causing the curving and broadening of the 
petiole, and opening on the opposite side by a transverse slit, with a whitish, slightly 
thickened, and elevated margin, recalling human lips. 
The writer has studied large numbers of galls of this species from 
Colorado and Louisiana, the latter collected by Mr. T. H. Jones. When 
fully grown, they vary normally from about 12 to 18 mm., extra sizes 
attaining 20 or even 25 mm. in their greatest diameter, which is usually 
