METAMORPHOSIS IN LEPIDOPTERA. 11 



of the male. Boisduval was one of the first authors who drew attention 

 to the variable number of moults that some lepidopterous larva? 

 appeared to undergo. He writes: — "Le nombre des mues varie peu 

 dans une meme espece, et peut-etre meme dans l'etat sauvage est-il 

 \ toujours constant ? Mais chez quelques chenilles velues que Ton eleve 

 f en captivite, il peut-etre augmente on diminue par une nourriture plus 

 ou moins abondante." Edwards has discussed at length that the 

 larva? of butterflies with a summer and a spring brood vary in 

 their moulting, the hybernating winter larvae moulting once more 

 than the summer larva?. He points out that "there seems to 

 be a necessity with the hybernators of getting rid of the rigid skin 

 in which the larva has passed the winter, at least in certain species 

 — Apatura, IAmenitis, &c. He adds that " in these cases, very little food 

 is taken between the moult which precedes hybernation and the one 

 which follows it. The skin shrinks, and has to be cast before the 

 awakened larva can grow. Those species (observed) whose larva? 

 moulted five times in the winter brood, required but four moults 

 during the summer. The larva is, in lethargy, actually smaller than 

 before the next previous moult." Dyar says (Psyche, iii., p, 161) that 

 the Arctiid larva? have a great capacity for spinning out their life- 

 histories by interpolated stages ; he thinks it is because so many of them 

 hybernate, and only a single brood extends through the season. The 

 early spring moult, before any feeding takes place, after hybernation, 

 is indulged in by the Anthrocerids, and must apparently be done in order 

 to get fid of the effete excretory matter that the skin represents. 

 Chapman considers that " Arctiids are typical hybernators. Many 

 of them have to half -hybernate, having warmth enough to keep 

 them awake, but not enough food for growth, but their tissues, at 

 least the chitinous ones of the cutis, and also, probably, and perhaps 

 especially, of the alimentary canal, become old and effete, and require 

 the rejuvenescence acquired by a moult. Other smooth-skinned 

 hybernators have similar capabilities." Packard considers that, " as 

 a rule, the greatest number of moults occurs in holometabolic insects 

 with the longest lives, and that an excessive number of ecdyses may 

 at times be due to some physical cause, such as lack of food combined 

 with low temperature." He says that, " in the winged insects, 

 especially Lepidoptera, the number of moults is dependent on climate ; 

 insects of wide distribution, growing faster in warmer climates, 

 consequently shed their skins oftener, e.g., the same species may 

 moult once oftener in the Southern, than in the Northern, States, as in 

 the case of Callosamia promethea which in West Virginia is double- 

 brooded." Weniger, by rearing the larva? of Antheraea mylitta and 

 Eacles impcrialis, which when reared under normal conditions have six 

 stadia, found that when reared in a warm moist atmosphere of about 

 25°C, they have but five stadia, i.e., they moulted but four times. In 

 the hot and moist climate of Ceylon, also A. mylitta has but five stadia 

 (Psyche, v., p. 28). 



Exact information as to the number of stadia through which in- 

 dividual- species pass is much desiderated. Dyar notes that Phyirarctia 

 isabella moults ten times, Ecpantheria scribonia, Scepsis, and Apateludes 

 eight times, and Seirarctia echo seven times. Buckler notes that Nola 

 centonalis moults nine times, the other species of the genus but six. 

 Packard gives Callosamia promethea as moulting three times. The 



