236 MEANS OF DEFENCE OF INSECTS. 



insect again to the test. — A similar apathy is shown by 

 some species of saw-fly (Tenfhredo, L.)^ which when 

 alarmed conceal their antennae under their body, place 

 their legs close to it, and remain without motion even 

 when transfixed by 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 exhi- 

 biting the slightest symptom of pain". 



There is a certain tribe of caterpillars called sur- 

 veyors (Geomet)'(e), that will sometimes support them- 

 selves for whole hours, by means of their posterior 

 legs, solely upon their anal extremity, forming an an- 

 gle of various degrees with the branch on which they 

 are standing, and looking like one of its twigs. Many 

 concurring circumstances promote this deception. The 

 body is kept stiff and immoveable, with the separations 

 of the segments 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 Avhich, it often 

 exhibits intermediate tubercles Avhieh increase the re- 

 semblance. 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. 

 Riisel's gardT?ner, 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 ani- 

 mal ''. 



But insects do not always confine themselves to at- 

 titudes by which they meditate escape or concealment; 



* Smcllie, Phil, of i\ut. llist. i. 150. " Kos. I. v. 21. 



