SEASONAL CHANGES AND HISTORIES. 141 



like the Cloudless Sulphur (Catopsilia Eubule) of 

 the Middle States, as a caterpillar and a butter- 

 fly ; this last instance is the more striking since 

 the insect appears to be unable to survive the 

 winter in the intermediate chrysalis stage. 



It is not always the cold of winter, however, 

 which causes an arrest of development ; for there 

 is a most extraordinary phenomenon in the life 

 history of some butterflies, which arises in mid- 

 summer ; viz., a period of lethargy or premature 

 hibernation. It may occur in the eggs, as in the 

 case we cited of some of the hair-streaks, where 

 these remain unhatched from July or August 

 until the next spring. It may also be found in 

 some chrysalids, where, as in the eggs, it is 

 merely early hibernation. But there are others, 

 and doubtless more than we know, where it as- 

 sumes peculiar characteristics. Notice, for exam- 

 ple, the Zebra Swallow-tail (Iphiclides Ajax) of 

 the south. This butterfly passes through the ex- 

 cessive number of four or five broods each season ; 

 but only a portion of the chrysalids of each brood 

 disclose the butterfly the same season ; the re- 

 mainder, in numbers constantly increasing with 

 each successive brood, go into premature hiberna- 

 tion, some even as early as June, and do not dis- 

 close the butterfly until the following spring ; so 

 that the spring brood of each year is made up of 

 fragments of all the last year's broods. One may 



