244 MEANS OF DEFENCE OF INSECTS- 



exhales^. Indeed there is scarcely any species in this 

 order that has not a peculiar scent. — Some dipterous 

 insects — though these in general neither offend nor de- 

 light us by it — are distinguished by their smell. Thus 

 Musca mystacea^ L., a fly that in its grub state lives 

 in cow-dung, savours in this respect, when a deni- 

 zen of the air, of the substance in which it first drew 

 breath. And another {M. ci/nipsea, L.) emits a fra- 

 grant odour of baum''. — I have not much to tell you 

 with respect to apterous insects, except that lulus ter- 

 restris, a common millepede, leaves a strong and dis- 

 agreeable scent upon the fingers when handled ''. Most 

 of the insects I have here enumerated, probably, are 

 defended from some enemy or injury by tl)e strong va- 

 pours that exhale from them ; and perhaps some in the 

 list produce it from particular organs not yet noticed. 



I shall next beg your attention to those insects that 

 emit their smell from particular organs. Of these, 

 some are furnished with a kind of scent-vessels, which 

 I shall call osmateria ; while in others it issues from the 

 intestines at the ordinary passage. In the former in- 

 stance the organ is usually retractile within the body, 

 being only exerted when it is used : it is generally a 

 bifid vessel, something in the shape of the letter Y. 

 Linne, in his generic character of the rove-beetles, 

 (Staphylinus), mentions two oblong vesicles as proper 

 to this genus. These organs, — which are by no means 

 common to the whole genus, even as restricted by late 

 writers, — are its osmateria, and give forth the scent for 

 which some species, particularly 5. hrunnipes^ are re- 



" Kirby, Mon. Jp. Jngl. i. 136. note a. " De Gcer, vi. 135. 3^. 

 « Ibid. vii. 581. 



