592 
Journal of Agricultural Research 
Vol. XIV, No. 13 
in the direction of the petiole of the leaf. The fundatrix, or stem mother, 
soon after hatching from the egg, locates upon the petiole of a very 
young opening leaf, causing it to curve and thicken, and form a trans¬ 
verse groove (PI. 81, B, a, b, c) at the point of attack. The petiole 
continues to thicken, and the groove to deepen, forming a pit or groove 
which carries the “louse” with it, and the two margins or lips gradually 
meet, inclosing the “louse” in a spacious cavity. The mouth or slit 
is usually transverse, but may be turned more or less in a vertical posi¬ 
tion, and the margins may, or may not, be thickened or protruded By 
the time the inmates become mature and ready to fly, the lips sepa¬ 
rate enough to allow the “lice” to pass out in search of the alternate 
food plants. The expanded petiole of the leaf can be easily seen ex¬ 
tending along the convex surface of the gall opposite the mouthlike 
opening. (For typical forms of this gall, see PI. 82; 84, A-E.) 
The gall of this species is readily separated from the galls of Pem¬ 
phigus populicaulis , which have a long curved opening formed by the 
twisting of the petiole upon itself, or from the galls of P. populi-ramu- 
lorum , which develop upon the side of tender growing twigs (PI. 84, 
A-E). 
LITERATURE CITED 1 
(1) Rilejy, C. V., and Monell, J. 
1879. NOTES ON The APHIDID.E OF THE UNITED STATES, WITH DESCRIPTIONS OF 
species occurring west of The Mississippi. In Bui. U. S. Geol. 
and Geog. Survey Territories, v. 5, no. 1, p. 1-32, pi. 1-2. 
(2) Oestlund, O. W. 
1887. synopsis of the aphidid^e of Minnesota. Geol. and Nat. Hist. Sur¬ 
vey Minn. Bui. 4, 100 p. Bibliography, p. 9-12. 
(3) Packard, A. S. 
1890. insects injurious to forest and shade trees. 5th Rpt. U. S. Ent. 
Comm., 956 p., 306 fig., 40 pi. 
(4) Williams, T. A. 
1891. HOST-PLANT LIST OF NORTH AMERICAN APHIDID-E. Univ. Nebr. Dept. 
Ent. Special Bui. 1, 28 p., 1 fig. 
(5) Osborn, Herbert. 
1892. catalogue of the hemiptera of iowa. In Proc. Iowa Acad. Sci., 
v. i, 1890/91, pt. 2, p. 120-131. 
(6) Bruner, Lawrence. 
1893. INSECT ENEMIES OF ORNAMENTAL AND SHADE TREES GROWING IN CITIES 
and parks. In Ann. Rpt. Nebr. State Hort. Soc., 1893, p. 166-235,72 fig. 
(7) Gillette, C. P., and Baker, C. F. 
1895. A PRELIMINARY LIST OF THE HEMIPTERA OF COLORADO. Colo. AgT. Exp. 
Sta. Bul. 31 (Tech. ser. 1), 137 p., illus. Works cited, p. 5-7. 
(8) Britton, N. L., and Brown, Addison. 
1896. AN ILLUSTRATED FLORA OF THE NORTHERN STATES, CANADA, AND THE 
British possessions. . . . v. i. New York. 
i More recently the writer has learned that as early as 1902 Dr. F. H. Chittenden recorded the receipt 
of specimens of an unknown species of Pemphigus from Texas. These were sent by Mr. S. A. McHenry, 
of the Beeville Substation of the Texas Experiment Stations, on February 14, 1901, with the information 
that the species was doing injury to the roots of cabbage in the vicinity of Beeville, some of the fields 
being reported as totally destroyed. (Chittenden, F. H. some insects injurious to vegetable 
crops. U. S. Dept. Agr., Div. Ent., Bul. 33, n. 3, p. 79. 1902.) 
