228 MEANS OF DEFENCE OF INSECTS. 



difficult to be attacked, or render them less palata- 

 ble. Thus the white froth often observable upon rose- 

 bushes, and other shrubs and plants, called by the vul- 

 gar frog-spittle, — but which, if examined, will be found 

 to envelop the larva of a small hemipterous insect 

 {Cicada spumaria, L.)? fi'om whose anus it exudes, al- 

 though it is sometimes discovered even in this con- 

 cealment by the indefatigable wasps, and becomes their 

 prey, — serves to protect the insect, which soon dies 

 when exposed, not only from the heat of the sun and 

 from violent rains, but also to hide it from the birds and 

 its other foes. — The cottony secretion that transpires 

 through the skin of many species of Aphis, Chermes, 

 and Coccus, and in which the eggs of the latter are often 

 involved, may perhaps be of use to them in this view; 

 either concealing them — for they look rather like little 

 locks of cotton, or feathers, than any thing animated — 

 or rendering ihem distasteful to creatures that would 

 otherwise prey upon them. — The same remark may 

 apply to the slimy caterpillars of some of the saw-flies 

 (Tent/irecio, L., T. Cerasi, Scrophularia;, S^c). The 

 coat of slime of these animals, as Professor Peck ob- 

 serves", retains its humidity though exposed to the 

 fiercest sun. — Under this head I shall also mention the 

 phosphoric insects : the glow-worm (Lampj/ris) ; the 

 lantern-fly {Fulgora); the fire-fly (Ela(er) ; and the 

 electric centipede (Scoiopendra electrica, L.) ; since the 

 light emitted by these animals may defend them from the 

 attack of some enemies. Mr. Sheppard once noticed a 

 Carabus running round the last-mentioned insect, when 

 shining, as if wishing but afraid to attack it. 



^ Nat. Hist, of the Shig-Kurm, 7. 



