HAWK MOTHS. 641 



the sides, and with an immensely long pink horn at the tail. 

 This horn soon begins to shorten, and finally curls round like a 

 dog's tail. As the larva grows older, it changes to a reddish 

 brown, and by the third month it entirely loses the caudal 

 horn. 



When about to enter the chrysalis state, it enters a short 

 distance into the ground, and soon works off the larval skin, 

 becoming a pupa of a dark brown colour. The moth generally 

 makes its appearance in the June of the following year, though 

 it has been known to issue in the same year, and in these 

 instances it doubtless becomes barren, as is the case with other 

 insects under similar circumstances. The colour of the perfect 

 insect is olive-grey, variegated with dark olive-green, as seen 

 in the illustration. 



The reader will note that very curious point in the history of 

 this larva, namely, the gradual change in shape, and lastly, the 

 disappearance of the horn at the end of its tail. The object of 

 these horns, which are common to the Hawk Moth larvae, is very 

 problematical. The creature never uses them in self-defence, 

 they are not venomous, not very sharp, and in some insects, such 

 as our Death's-head Moth, are blunt and rounded at the tips. 

 jSTor is it likelv that birds would be afraid of them, for the instinct 

 of birds tells them whether or not an insect be fit for their 

 food. And here we have an instance where, when the larva is 

 very small and inconspicuous, the horn is very long. When it 

 becomes larger and more easily seen, the horn curls up so as to 

 lose all offensive aspect, and when it becomes a large and con- 

 spicuous larva, the horn disappears altogether, and leaves the 

 creature defenceless. That the horn must serve some needful 

 purpose is evident by the fact of its existence, but what that 

 purpose may be is at present a complete mystery. 



Owing to the exigencies of space, I am reluctantly compelled 

 to have the figure of Macrosila cruentus much reduced. 



It is a very giant among Hawk Moths, being so large that the 

 specimen in the British Museum can only just be got into a 

 drawer, its tail touching the head of the drawer, and the tip of 

 its enormous proboscis reaching to the foot. The measurement of 

 its expanded wings is rather more than seven inches, the proboscis 

 alone measures nine inches and a quarter, and the total length 



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