MEANS OF DEFENCE OF INSECTS. 283 



tation to put the constancy of the poor insect again to 

 the test. A similar apathy is shown by some species of 

 saw-flies (Serrifera), 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 motion- 

 less ; and when in this situation, they may be pierced and 

 torn to pieces without their exhibiting the slightest sym- 

 ptom of pain a . 



There is a certain tribe of caterpillars called surveyors 

 (Gcometra), 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 

 promote this deception. The body is kept stiff and im- 

 moveable 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 which, it often exhibits intermediate tubercles 

 which increase the resemblance. Its colour too is usually 

 obscure, and similar to that of the bark of a tree. So 

 that, doubtless, the sparrows and other birds are fre- 

 quently deceived by this manoeuvre, and thus balked of 

 their prey. Rb'sel'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 b . 



But insects do not always confine themselves to atti- 

 tudes by which they meditate escape or concealment ; 

 Sraellie, Phil, of Nat. Hist. i. 150. b Ros. I. v. 27. 



