384 LEPIDOPTERA 



CHAP. 



two long, flexible whips, capable of being thrust out, and with- 

 drawn, with rapidity. The structure and the mode of action of 

 these flagella have been well elucidated by Professor Poulton. 1 

 The flagella are to be considered as actual prolongations of the 

 receptacle in which each is placed, though they _ are of very 

 different texture therefrom ; they are everted by blood-pressure 

 and drawn in by muscular action ; this latter function is very 

 perfectly accomplished, the amount of relaxation and contraction 

 of the muscle being very great. It has been maintained that 

 the whips have arisen as arms of protection against the attacks 

 of Ichneumon flies ; observation shows, however, that the pro- 

 portion of these " protected " Insects destroyed by enemies of this 

 sort is quite as large as it is in the case of forms that are not so 

 protected. The Puss-moth larva is also believed to be protected 

 by terrifying attitudes, 2 as well as by ejection (like so many other 

 larvae and insects generally) of fluid. There is no reason for 

 believing that these larvae are less eaten than others, and con- 

 sequently a further hypothesis has been proposed, to the effect 

 that if they had not acquired these means of defence they would 

 have been exterminated altogether. This supposition is con- 

 sidered to account for their acquiring the defence by means of 

 natural selection ; realising the dictum of D. O'Phace, Esq. 



Some flossifers think that a fakkilty's granted, 

 The minnit it's proved to be thoroughly wanted. 



When the Puss-moth caterpillar is full grown it spins a peculiar 

 cocoon of a solid and impervious nature, which it manages to make 

 look very like the spots, crevices, or other places amongst which 

 it is located ; in this prison the creature remains for nine or ten 

 months by far the larger part of its existence. When it has 

 changed to a moth it has to escape from the cell in which it so 

 effectually confined itself. This is effected by the cocoon being 

 thinner in front of the head of the moth, and by the emission 

 from the alimentary canal of a fluid that softens the cocoon at 

 the spot alluded to. Mr. Latter has ascertained 3 that this fluid 

 is strongly alkaline, and contains potassium hydroxide. The 

 front of the head of the moth is provided with a shield, consist- 

 ing of a portion of the pupa shell, which enables the moth to 



1 Tr. cut. Soc. London, 1887, p. 297, PI. x. 

 2 See Poulton, Tr. cnt. Soc. London, 1886, etc. 3 Op. cit. 1895, p. 399. 



