14-8 INTERNAL ANATOMY OF INSECTS. 
the remarkable odour of Fraxinella: the larva of another 
species of this genus (C. Rosa) has an odour which 
seemed to Reaumur as attractive to cats as that of Nc- 
pcta cataria or Tcucrium Marum " : some Phalangia 
smell like walnut leaves 1 '; and the various species of the 
genus Prosopis (Mc/ifta * b. K.) have a very agreeable 
scent of Dracocephalum moldavicum h . 
We next come to fetid odours. These in nume- 
rous cases are known to be secreted and emitted by ap- 
propriate vessels and organs ; they are often exhaled 
from a fluid secretion, of which, in the letter lately re- 
ferred to, I gave you almost all the known instances. 
Savi, in his history of lulus Jcetidissimus, informs us that 
it emits a yellow fetid fluid from its supposed spiracles, 
which if applied in sufficient quantity imparts a red co- 
lour to the skin, to be removed neither by friction nor 
washing, but only disappearing by time; when removed 
from the black vesicles in which it is stored, it shoots 
into very transparent octoedral crystals . 
I have before mentioned the coloured fluid which 
some insects emit when they are disclosed from the 
pupa, and that it probably exhales some powerful odour 
which attracts the males d . 
The great Hydrophilus, in its larva state, when first 
taken into the hand remains without motion ; in a mi-- 
nute afterwards it renders itself so flaccid as to appear 
like a cast skin. Taken by the tail it contracts itself 
considerably, it then agitates itself briskly, and ejaculates 
with a slight noise a fetid and blackish fluid e . 
• l Reaum. iii. 494. h Mon. Ap. Angl. i. 136. 
c Osservaz.su/lo lulus, §c. 14. d Vol. III. p. 21)7— . 
c JV. Diet. d'Hist. Nat. xv. 487. 
