THE YOUNG NATURALIST'. 



245 



greasy. The pupa? of the Geometrae do not 

 always undergo their metamorphosis beneath 

 the soil, whilst the far larger number of the 

 Noctuae are subterranean. 



The shapes and external appearance of 

 Pupae are very dissimilar. Those of the 

 Sphingida? are remarkable for the great 

 development of the sheath containing the 

 tongue. Certain species are covered with a 

 delicate bloom, like that of a purple plum, as 

 with Diloba Cerukeocephcda and Cidaria Psitta- 

 cata, and amongst the Eupithecia may- 

 be found really quite bright and striking 

 curious net-work follicle, the colours and 

 markings bear a great similarity to the 

 perfect insect. The Pupae of Nocture so 

 closely resemble one another in many 

 instances that it is well nigh impossible to 

 pronounce upon the identity of the species 

 unless the larva has been previously re- 

 cognised. 



The duration of the pupa state varies al- 

 most as much as the moths themselves. It 

 is also influenced by external circumstances. 

 Cossus Lignipevda, the Goat moth, having 

 been known to remain in the pupa for six, 

 seven, or even more years. This probably 

 is the reason why some years one species 

 may appear in abundance, as was the case with 

 Colias Editsa in 1877, and Plusia Gamma in 

 1879. What these externa: circumstances 

 may be, however, it has hitherto bahied all 

 our investigations to discover. The period 

 of the pupal state may be artificially extend- 

 ed or diminished, and the plan of " forcing " 

 pupae is one frequently resorted to by the 

 collector. During the bitter weather which 

 prevailed in January, by keeping some larvae 

 of the rare little Acidalia Degeneraria over the 

 mantel-piece, I was able to get this species to 

 feed up, pupate, and emerge in a fortnight or 

 three weeks. 



The third stage with lepidopterous insects 

 is one of almost absolute quiescence, in fact, 

 with the exeption of a few wrigglings with 

 the tail segments, they are capable of no 

 other movements. This statement must be 



I qualified though somewhat in the case of the 

 internal pupae of the Sesida and Zeuzeridce, 

 which are furnished with a series of hooks on 

 each segment, by which means they are en- 

 ; abled to move up and down the hollow stems 

 of the plants in which they have pupated, 

 j and push themselves half through the hole 

 ; of egress when emerging. 



There is but one lepidopterous insect 

 ; which can produce any sound audible to our 

 ' ears, this is the Acherontia Atropos, or Death's 

 \ Head Hawk moth. Till the year 1878, 

 when the insect was more plentiful than 

 ! usual, I had never heard the sound myself, 

 although from time to time several specimens 

 fell into my hands, and I began almost to 

 question the veracity of the statement 

 1 respecting it. In that year all my doubts 

 were set at rest, for every moth that 1 

 possessed was a veritable " squeaker," and 

 not only so, I had the good fortune to hear 

 both larva and pupa likewise make this 

 noise, which is very similar to, and quite as 

 loud as, that of a mouse under the " tender 

 mercies " of puss. Endless discussion has 

 arisen, and is by no means at an end, as to 

 the means by which the stridulation is 

 produced. The favourite opinion is that " it 

 is connected with a small membranous cap- 

 sul which is situated on either side of the 

 body at the base of the abdomen, and which 

 is covered with some hairs that can be 

 made to vibrate." If such be the case how 

 are we to account for the identical sound 

 made by the larva and the pupa, both of 

 which are perfectly smooth and without 

 hairs ? I will only add that every time my 

 pup;e were treated in their mossy blanket to 

 a shower bath, they expressed their approval 

 or disapproval with sundry squeaks, and 

 that in the case of the imago I cannot help a 

 suspicion that the sound is made by the 

 proboscis, and my reason is this, when 

 needing them for my cabinet, compelled to 

 put them to death, I always caught hold of 

 them at the base of the wings, so that they 

 could struggle only with their legs, and the 



