60 BRTTISH BUTTERFLIES. 



(Eurymus), and adds that, " as the leaflets of the foodplant close at 

 night, this would seem to be a necessary one, and also probably 

 induces a habit of feeding only by day." This habit is strange, 

 for the larvae of Colias hyale and C. edusa, in their first two stadia, 

 select the upperside and feed only by day, apparently for the specific 

 purpose of being shut in by the closing leaves at night. Scudder 

 adds that, " when not feeding, the caterpillar invariably stretches 

 itself out at full length, either along the stalk of the plant or the 

 midrib of one of the leaflets, which, being of the.same colour as they, 

 and the stigmatal stripe resembling in its straightness and stiffness 

 the midrib of the leaflets themselves, its detection is very difficult," 

 so that, in this habit, the larva of E. lisa much resembles those of 

 C. edusa and other typical Coliads. When disturbed, the larva raises 

 the front portion of the body barely above the surface, and, swings 

 it from side to side in a slow but deprecatory manner, but, if roughly 

 handled, it will drop from the leaf, spinning a thread and hanging 

 thereby. Another of the southern Nearctic Cassia- feeding species with 

 larval habits that appear to be almost identical with those of Eurema 

 lisa is Eurema (Xanthippe) nicippe. With its home in the southern 

 States, it is there continuously-brooded, the larvae feeding on rapidly 

 and producing " forwards " in every brood. Of the irregularity in the 

 rate at which the larvae mature, one may quote Edwards' observation, 

 that, one day in September, 1875, he cut a branch of Cassia on which, 

 at the moment, were newly-laid eggs of Eurema nicippe, larvae in every 

 stage of growth, and a butterfly of the same species just emerged and 

 still resting on the empty shell of its chrysalis. The October larvae 

 produce imagines in November, and these are said to reappear in 

 April— a statement that has led some entomologists to the view that 

 it hybernates in the imaginal state. Although not definitely worked 

 out, it is supposed by the American entomologists that the species has 

 not a winter-feeding larva, nor do any of the authorities suggest that 

 the November and April imagines are from the same brood of larvae 

 maturing at different rates. The larva in general appearance, however, 

 is said to resemble those of Colias, as also does that of Eurema lisa, 

 but the latter is more slender. 



Of the larval habits of the Ca.ss?a-feeding Callidryads (Catopsilias), 

 both of the Old and New Worlds, practically nothing is known. One 

 suspects that real study would discover many interesting facts. But 

 our ignorance is profound. It would appear that in its southern 

 haunts, the Nearctic Callidryas eubule is quite continuously-brooded, 

 that just as Colias edusa spreads in Europe, so this species spreads in 

 North America, and, just as our text-books, based on imperfect know- 

 ledge, often state categorically that the latter is double-brooded in 

 northern Germany, Britain, etc., so the American text-books incline to 

 this opinion concerning C. eubule in the more northern parts it reaches. 

 There appears to be no doubt that it immigrates into, and is annihilated 

 continuously in , these areas, the species taki n g i ts man y-brooded , forward - 

 producing, southern, larval habits with it into northern climes and 

 being killed out, just as is C. edusa with us. 



The food-habit of this group appears to be a very constant one, for 

 Cassia is the chosen pabulum in districts as far apart as the United States 

 of America and Sumatra. In America, Callidryas eubule selects Cassia 

 chamaecrista, whilst in Sumatra, Catopsilia crocale chooses Cassia 



