760 



AN INTRODUCTION TO ENTOMOLOGY 



whitish saddle on the middle segment of the abdomen. The tubercles 

 on the second thoracic segment are club-shaped and spiny. 



The larva of the viceroy feeds upon willow, poplar, balm of gilead, 

 aspen, and cottonwood. The species is two- or three-brooded and 

 hibernates as a partially grown larva in a nest made of a rolled leaf. 

 (Fig. 969, c). This nest is lined with silk, and the leaf is fastened to 

 the twig with silk so that it cannot fall during the winter. So far as 

 is known all of the species of the sovereigns hibernate as larvas in 

 nests of this kind. It is worthy of note that only the autumn brood 

 of caterpillars make these nests; so that the nest -building instinct 

 appears only in alternate generations, or even less frequently when the 

 species is more than two-brooded. B. archippus is found over nearly 

 the whole of the United S-'ates as far west as the Sierra Nevada 

 Mountains, and has been found sparingly even to the Pacific coast 

 near our northern boundaries. 



The vice-reine, Basildrchia archippus floridensis . — ^This is a variety 

 of Basilarchia archipptts that is much darker than the typical form; 

 the ground color of the wings resembling that of the queen, Danaus 

 berenice. As it is found in the same region as the queen it is supposed 

 to mimic that species, hence the popular name suggested above. 



V. THE EMPERORS 



This group is poorly represented in our fauna; our best-known 

 species are the two following, which occur in the South. 



The tawny emperor, Chlonppe clyton. — In this and the following 

 species the apex of the front wings and the anal angle of the hind 

 wings are considerably produced in the males, but more rounded in 

 the females. The 

 male is represented 

 in Figure 970 and 

 the dotted line at 

 the left indicates 

 the contour of the 

 wings of the female. 

 This excellent fig- 

 ure is from the sixth 

 Missouri report by 

 C. V. Riley, where 

 a detailed accoimt 

 of the life-history 

 of the species is 

 given. The wings 

 of this butterfly are 

 more or less ob- 

 scure tawny, mark- 

 ed with blackish brown, and with pale spots. Thers is a submargi 

 nal row of six eyelike spots on the hind wings. 



Fig. 970. — Chlorippe clyton: a, eggs; b, larva; c, pupa; 

 d, upper surface of rriale butterfly; the dotted line at 

 left indicates the contour of the wings of the female. 

 (From Riley.) 



