618 TEXT-BOOK OF ENTOMOLOGY 



larval stages, but six and seven stages are not infrequent, while 

 there are seven in Seimrctia echo, eight in Ecpantheria scribonia, 

 Scepis, and Apatelodes, and nine and ten in arctians, while the 

 European Nola centonalis moults nine times, other species of this 

 genus shedding their skins six times. (Buckler.) (Psyche, v, 

 pp. 420-422.) Callosamia promethea appears, as a rule, to moult 

 but three times. Orgyia antiqua was found by Hellins to moult 

 from three to five times. Riley found that in 0. leucostigma the 

 males moult four times, the female four, but sometimes five times, 

 while Dyar states that in 0. cjnlosa the male larvae moult three or 

 four times, the female always four times ; in 0. antiqua, however, 

 there are six stages, and in the female seven. Lithocolletis, Cham- 

 bers think;?, as a rule, moults eight times, and Comstock thinks that 

 L. Jiamadryadella casts its skin seven or eight times. 



In the blow-fly (Calliphora) Leuckart and Weismann have inferred 

 at least t\vo moults, while Weismann suspected that there are as 

 many as four. In Musca domestica we have observed that the 

 larva moults three times ; in (Estriclse there are three larval stadia. 

 (Brauer.) In Corethra there are four larval moults, and Miall 

 thinks there are probably as many in Chironomus. Passing to the 

 phytophagous Hymenoptera, there are three moults or four larval 

 stages in Nematus erichsonii, but Dyar informs us that less than 

 four stages in saw-fly larvae is very rare, that he has only one record 

 of less than five, and that that is doubtful; "five for nematid, six 

 and seven for others, is certainly the rule. The highest I have is 

 the indication of 11 stages for Harpiplioms varianus, but this again 

 is an inference only, and attended with doubt." (Can. Ent., xxvii, 

 p. 208.) In Bombus we have observed five different sizes of larvae, 

 and hence suppose the least number of ecdyses is five, while we are 

 disposed to believe that this insect, as well as wasps and bees, in 

 general shed their skins as many as eight times during their entire 

 existence. 



The honey-bee, Cheshire thinks, since he has found the old and 

 ruptured pellicles, probably moults six times before it spins its 

 cocoon, or passes into the semipupa condition. (Bees and Bee- 

 keeping, p. 20.) 



As to the cause of the great number of moults in the arctians and 

 in the beetles experimented with by Riley, it would seem that cold 

 and the lack of food during hibernation were the agents in arctians, 

 and starvation or the lack of food in the case of the beetles, such 

 cause preventing growth, though the hypodermis-cells retained their 

 activity. 



