236 MEANS OF DEFENCE OF INSECTS. 
a pin.—Spiders also simulate death by folding up their 
legs, falling from their station, and remaining motionless ; 
and when in this situation, they may be pierced and torn 
to pieces without their exhibiting the slightest symptom of 
pain?. | 
There is a certain tribe of caterpillars called surveyors 
(Geometre), that will sometimes support themselves for 
whole hours, by means of their posterior legs, solely upon 
their anal extremity, forming an angle of various degrees 
with the branch on which they are standing, and looking 
like one of its twigs. Many concurring circumstances pro- 
mote this deception. The body is kept stiff and immovea- 
ble with the separations of thesegments scarcely visible ; it 
terminates in a knob, the legs being applied close, so as 
to resemble the gem at the end of a twig; besides which, 
it often exhibits intermediate tubercles which increase the 
resemblance. Its colour too is usually obscure, and si- 
milar to that of the bark of a tree. So that, doubtless, 
the sparrows and other birds are frequently deceived by 
this manoeuvre, and thus balked of their prey. Ro6sel’s 
gardener, mistaking one of these caterpillars for a dead 
twig, started back in great alarm when upon attempting 
to break it off he found it was a living animal>. 
But insects do not always confine themselves to atti- 
tudes by which they meditate escape or concealment ; they 
sometimes, to show their courage, put themselves in a 
posture of defence, and even have in view the annoyance 
as well as the repelling of their foes. The great rove- 
beetle (Staphylinus olens, F.) presents an object sufficiently 
terrific, when with its large jaws expanded, and its abdo- 
men turned over its head, like a scorpion, it menaces its 
@ Smellie, Phil. of Nat. Hist. i. 150. b Ros. lv. 27% 
