26 ; 
hamamelidis, the generic name of Hamamelistes will have to be 
retained for this species. 
In 1879 it was again partly described by Prof. C. V. Riley in the 
Bulletin No. 1 of Volume V of the U. 8. Geol. and Geog. Survey, 
p. 14, who erroneously referred it to Hormaphis. 
Mr. O. W. Oestlund, while studying the Aphides of Minnesota, 
described an insect, which he found to corrugate the leaves of birches, 
in Bulletin 4, of the Geological and Natural History Survey of Minne- 
sota, page 17, 1887, under the name of Hormaphis papyracee, not 
being aware that he had discovered the return migrant of Hamame- 
listes spinosus. The complex history of these two remarkable species 
has remained a sealed book up to the present time, when, at last, it 
has been solved. 
My own acquaintance with the birch-inhabiting form of this species 
dates back to May, 1887, when I discovered the younger stages of it 
on the young leaves of a small birch at Richfield Springs, N. Y., but 
failed, on account of the immature state of the insects, to recognize its 
generic position. It was again found by me in June, 1895, on leaves 
of young birches at Charlton Heights, Md., in various stages of devel- 
opment, including the migrant, but considered it to be a new species 
of Hormaphis, which I later found to have been described by Mr. 
Oestlund. My failure to recognize it at that time as the return 
migrant of spinosus was in a great measure due to the fact that at the 
date of finding these migrants on the birches I observed also young 
galls of spinosus on the witch-hazels. eg 
The geographical distribution of this species depends in a great 
measure on the presence of both plants in the same locality. In 
favorable seasons it may become so numerous as to cause great injury 
to the foliage of birches, inducing the leaves to fall prematurely. 
Winter egg (Fig. 12).-—-The winter eggs of this species, unlike 
those of Hormaphis hamamelidis and the majority of other Aphids, 
are deposited from about the middle of June to early in July, instead 
of during the fall of the year, and hatched by the end of May or 
early in June the following year, remaining dormant almost a whole 
year, whereas in the other species it takes only about one-half of that 
time. These eggs are commonly deposited between or near the 
crotches formed by the twigs and petioles of the flower buds, the 
sears left by previous flowers or seed capsules, and in crevices of the 
bark, or similar sheltered positions. That the instinct of the migrant 
is rather defective in selecting the proper shrubs of witch-hazel 
for the continuance of its race has been demonstrated by the fact 
that it will migrate indiscriminately to both the bearing and imma- 
ture plants, on account of which the young stem-mother, hatching 
from eggs deposited on immature plants, is doomed to perish through 
absence of flower buds on which to settle. JI have repeatedly found 
large numbers of the sexes and their winter eggs on immature 
