Sept. 23,1918 
Pemphigus populi-transversus 
589 
The stem mother (fundatrix), after issuing from the egg, makes its 
way to the young leaves of the poplar, where it settles down on a petiole. 
Here a gall begins to form about it. 
DESCRIPTIONS OF STAGES OF PEMPHIGUS POPULI-TRANSVERSUS AND 
ITS GALL 
By C. P. Giixette 
Examples of this species in the collection of the Colorado Experiment 
Station, which were collected by Mr. J. T. Monell at St. Louis, Mo., 
on October 2, 1907, agree in every particular with Riley's description of 
the winged form, except that the fifth joint of the antenna is not quite as 
cylindrical as the description would indicate. Specimens sent by Mr. 
T, H. Jones, of the Bureau of Entomology, which were collected from 
similar galls at Baton Rouge, agree perfectly with the Missouri speci¬ 
mens, and with specimens taken at many different times in Colorado. 
Winged and wingless “lice" taken by Mr. E. S. Tucker, then of the 
Bureau of Entomology, from the roots of turnips at Baton Rouge, on 
March 6, 1915; by Mr. F. B. Paddock, State Entomologist, on turnips, 
at College Station, Tex., on February 13, 1914; and by Mr. T. H. Jones 
on Brussels sprouts at Baton Rouge, on March 4, 1916, agree well in 
structural details. 
The galls are widely distributed over Colorado upon the broad-leaved 
cottonwoods; but they are not abundant, except upon an occasional 
tree. It should be stated here that the sexupara of this species is sepa¬ 
rated with some difficulty from the same form of Pemphigus betae . In 
the latter species, however, the permanent sensorium of joint 5 is of the 
normal form and never broad and irregular, inclosing chitinous islands, 
as in populi-transversus, and the spur is distinctly longer. 
Fundatrix, first instar. —Described from specimens reared by Mr. 
T. H. Jones at Baton Rouge, La., and taken from the galls on March 
3, 1916. 
Ground color pale yellow tinged with green; head black; wax plates dusky; length, 
0.60 mm.; width, 0.23 mm.; antenna, 0.45 mm., 4rjointed, joints 1, 2, and 3 subequal in 
length, joint 4 with spur, almost as long as 2 and 3 combined and very stout, and with 
several transverse rows of small chitinous points; all femora stout, the greatest width 
of the hind femur nearly equalling one-half its length; six longitudinal rows of wax 
plates upon the dorsum of segments 1 to 6 of the abdomen, and four rows of larger 
plates upon the dorsum of the thorax, each plate bearing at least one short, stout 
hair; legs and antennae deep shining black with a few short stout gray hairs (PI. 81, A). 
Adult fundatrix. —Described from living specimens taken at Fort 
Collins, Colo., by Mr. L. C. Bragg, Assistant Entomologist of the Colorado 
Experiment Station, on September 22, 1916, from galls on leaves of 
Populus deltoides. The opening of the gall was a straight, transverse, or 
somewhat diagonal slit, passing from one-half to two-thirds of the way 
across the gall, but not a narrow and protruded mouthlike or liplike 
70395°—18 - 2 
