Sphingidae 
present themselves, will recognize the propriety of the separa¬ 
tion, which has been made. 
(i) Pachysphinx modesta Harris, Plate VII, Fig. i, 8 . 
(The Big Poplar Sphinx.) 
Syn. princeps Walker. 
Form occidentalis Henry Edwards, Plate VII, Fig. 2, ? . 
(The Western Poplar Sphinx.) 
Syn. imperator Strecker. 
This noble hawkmoth feeds in the larval stage upon various 
species of the genus Populus and upon willows. There are a 
number of local races or subspecies, two of which we give ; the 
common eastern form and the western variety. The latter may 
at once be distinguished by its generally paler coloration. It 
ranges over the United States and as far south as northern 
Mexico. 
Genus CRESSONIA Grote & Robinson 
There is but one species in this genus. The insect is easily 
recognizable, in spite of the fact that it varies considerably in the 
color of the wings. 
(1) Cressonia juglandis Abbot & Smith, Plate VI, Fig. 9, $ . 
(The Walnut Sphinx.) 
Syn. instabilis Martyn; pallens Strecker; robinsoni Butler. 
The caterpillar feeds upon the black walnut, the butternut, 
and the hop-hornbeam. Some of the larvae are green, others are 
reddish, but the color of the larvae seems to have no relation to 
any variation in color of the perfect insects. The species is dis¬ 
tributed from Canada to Florida and westward to the eastern 
boundary of the great plains. 
SUBFAMILY SESIIN/E 
Genus PSEUDQSPHINX Burmeister 
There is but one species in this genus, which is structurally 
closely related to the species falling into the genus Erinnyis. It 
is a characteristic insect of the American tropics, and possesses a 
very wide range. 
(1) Pseudosphinx tetrio Linnaeus, Plate VI, Fig. 2, 8 . 
(The Giant Gray Sphinx.) 
Syn. plumeria Fabricius; ruslica Sepp; hasdrubal Cramer; asdrubal 
Poey; obscura Butler. 
57 
