Sphingidae 



present themselves, will recognize the propriety of the separa- 

 tion, which has been made. 



(i) Pachysphinx modesta Harris, Plate VII, Fig. i, $. 

 (The Big Poplar Sphinx.) 



Syn. prince ps 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. 



(i) Cressonia juglandis Abbot & Smith, Plate VI, Fig. 9, $ . 

 (The Walnut Sphinx.) 



Syn. instabilis Marty n; pollens 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 PSEUDOSPHINX 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. 



(i) Pseudosphinx tetrio Linnaeus, Plate VI, Fig. 2, $ . 

 (The Giant Gray Sphinx.) 



Syn. plumerice Fabricius; rustica Sepp; hasdrubal Cramer; asdrubal 

 Poey; obscura Butler. 



57 



