THE CANADIAN ENTOMOLOGIST. 



the head as the larva moves about. When at rest the neck and head are 

 wholly withdrawn, and as the former, when fully extended, is considerably I 

 longer than the depth of the second segment, it must possess much 

 elasticity.* The larva feeds on the inner part of the bud, and to get at 

 this cuts away the surface on one side till a hole is made just big enough 

 to admit its head ; and as it feeds the second segment is pressed hard 

 against the bud so as to permit the utmost elongation of the neck. Thus 

 it -is enabled to eat out the contents of the bud, and only desists when 

 there remains but the empty shell. When so engaged the anterior seg- 

 ments are curved up and the others rest on the stalk of the plant. But 

 very small larvae' rest wholly on the bud, curving about it. I have not seen 



* Note. — In a recent paper by Mr. Scudder, " On the Classification of Butterflies 

 with special reference to the position of the Equites or Swallowtails," Trans. Am. Km. 

 Soc. vi., 69, 1877, the special object of which is to argue for the degradation of the 

 Papilioninse, 1 find the following lines : "The Equites and Ephori" (by this last obso- 

 lete appellation the uninitiated may understand some division which includes the 

 Lycaenidse) • • • "are closely related to each other and disagree with all other groups 

 in tin- retractility oj the head of the caterpillar." This sweeping assertion is fortified by a 

 quotation thus : " 1 do not know that attention has ever been drawn to this feature in 

 the caterpillars of Equites since the time of Denis and Schiffermuller, who say, Syst. 

 Verz. Schmett. Wien., 161, 1775, 'When at rest the head is nearly half concealed by 

 the extended epidermis of the first body segment, and can be compared with nothing in 

 other butterfly caterpillars, excepting the complete retractility of the head in I.ycaenids.'" 

 I observe that the authors quoted by Mr. Scudder do not say that the head is retractile, 

 but that it lies " nearly half concealed by the extended epidermis of the next segment." 

 There is nothing that can properly be called retractility of the head in any Papilio larva ever 

 bred by me, and this will cover ajax, troilus, asterias, turnus, cresphontes and philenor. 

 The head of Lycaena pushes out like the upper joint of a microscope and it is as com- 

 pletely retractile as the head of a turtle. The head of Papilio is partly covered by the 

 extended epidermis of the next segment, which forms a sort of collar, and this 

 segment is unusually broad as compared with larvae of other families, probably 

 in order to afford room for the tentacles and muscular apparatus connected 

 with them. As the larva feeds, the head has a vertical movement, and when the 

 jaws are raised, the top of the head is turned down a little into the collar. Hut as to 

 any ability in Papilio to push out and draw in its head beyond that of any species of the 

 Nymphalida.', for example, it does not exist. A caterpillar of Argynnis will rest on its 

 hinder legs and extendi its body fifty per cent, beyond the length it assumes when at rest, 

 and unless its joints were cast iron, some power of extension must belong to every jointed 

 creature ; and the neck of the caterpillar, which is nothing but the connection between 

 the first and second segments, stretches just as the rest of its body stretches, perhaps a 

 little more, but in no different manner. That is another thing from " retractility." One 

 might a* well say that a man's head is retractile when he wears a high shirt collar. 



