SMELL IN INSECTS. 55 



It is by no means improbable that many insects 

 employ the offensive odours which nature has enabled 

 them to discharg-e, to produce effects of terror upon 

 their enemies. Perhaps the most familiar instance of 

 this occurs in the extensive family of bug's {Cimicidce)^ 

 the foetor of which is always similar, though their food 

 is so various; and the pretty little beetles, the lady- 

 birds {Coccinellidce)^ of which children are so fond, 

 emit a similar, though not quite so offensive an odour. 

 The rove-beetles (StaphyllnidfE), in addition to their 

 threatening and formidable attitudes, emit a very 

 disagreeable odour, though it is not quite so bad as 

 that of others {Silphidce) which feed on carrion. The 

 church-yard beetle^ (Blaps mortisaga) has been noted 

 for the same circumstance since the time of Pliny -f. 

 Some bees {Andrenidce)^ again, have a strong smell of 

 garlic, which may probably be disagreeable to their 

 various enemies %. We have had an opportunity of 

 examining the curious organ, supposed to be intended 

 for the similar purpose of defence, in the very beautiful 

 caterpillar of the swallow-tailed butterfly {Papilio 

 Machaon, Linn.), three of which we took upon fen- 

 nel in the Jardin des Plantes, at Paris. The cater- 

 pillar itself is of a fine green, banded with black. 

 The instrument in question § is of a dark orange, and 

 is always concealed within one of the rings on the 

 shoulders, unless the creature be irritated, when it 

 darts it out to the extent of about an inch, and at the 

 same time emits a strong odour resembling fennel. 

 This may be intended to intimidate the ichneumons 

 from depositing their parasite eggs in its body, or 

 warning off the thrushes or the carnivorous locust 

 {Acrida verrucivorii) from devouring it. On the 



* Figured in Insect Transformations, p. 241, 281. 

 f Hist. Nat. xxix. 6. l Kirby, Monographia, i. 136, 

 § Figured in Insect Transf. p. 281, a. 



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