8 
The earliest, a rather brief record and description of this interest- 
ing Aphid, was published by Dr. Asa Fitch in 1851, in his ‘‘Cata- 
logue of the Homopterous Insects of the State of New York,” under 
the name of Byrsocrypta hamamelidis. Ten years later it was 
redeseribed by Baron von Osten Sacken in the Stettiner Entomologische 
Zeitung (p. 422, 1861), under the generic name of Hormaphis, using 
the identical specific name adopted by Fitch, though not being aware 
of its having been described by Fitch under the same name, and 
erecting for ita new genus. A translation of this description, by b. D. 
Walsh, will be found in the Proceedings of the Entomological Society 
of Philadelphia, 1866-67 (p. 281). In 1867 it was again described by 
Dr. Henry Shimer, in the Transactions of the American Entomolog- 
ical Society of Philadelphia (vol. 1, p. 283), under the name of Hama- 
melistes cornu, with a rather full description of the gall and its arehi- 
tects. Excepting a short description of the gall and the winged insect, 
by Prof. Cyrus Thomas, in the Transactions of the Illinois State Hor- 
ticultural Society for 1876, published in 1877 (p. 199), nothing addi- 
tional regarding the history of this interesting species has been 
published. 
The writer’s observations regarding this species were begun at 
Washington, D. C., in the spring of 1878, and were continued with 
varying success until the end of 1899, when they reached a successful 
termination. 
As with other gall-producing plant-lice, the study ot the galls and 
their architects is comparatively easy, but, with the departure of the 
winged migrants, continuous observations are suddenly interrupted 
and the track lost, leaving no trace as to the whereabouts of the inter- 
mediate generations. Migration from the host plant takes place gen- 
erally during spring or summer, the return migrants making their 
reappearance from early in September till late in the fall, to restoek 
their host with eggs. 
What becomes of this particular species during the intervening 
time after leaving its gall remained a profound mystery to the writer for 
many years, notwithstanding continuous efforts to solve the problem. 
Accidentally, while on a collecting trip near Tacoma, D. C., in Sep- 
tember, 1890, the writer observed a peculiar Aphid inhabiting the 
under side of the leaves of a small shrub of Betula nigra, but failed 
at that time to recognize it as the missing link of Hormaphis. During 
the following seven years nothing additional was discovered to cause 
me to continue observations, this being due in a great measure to the 
destruction of large numbers of witch-hazel bushes and young birches, 
and the consequent scarcity of galls in the woods surrounding the city 
of Washington. Fortunately, however, I discovered in September, 
1897, a number of witch-hazel trees and bushes, as well as young 
birches, in a narrow and protected valley near the edge of a small 
ereek at Cabin John Bridge, Md., where I found numerous old and 
