CHAP. IV. | MEANS OF DEFENCE IN INSECTS. 37 



ground and lie motionless, thus escaping detection. Instances 

 might be quoted in almost all Orders but are most commonly seen 

 amongst Moths and Beetles. The Weevils especially arc noted for 

 exhibiting the " death-feint," a namegiven toa special manner in 

 which the limbs arc held rigidly contracted ; this is accomplished 

 by a voluntary stiffening of the muscles, as is shown by inducing 

 the " death-feint " repeatedly in one individual, when the periods 

 become shorter as the muscles become tired. 



An observer will soon discover that many insects, in an appa- 

 rently deep state of quiescent rest on tree-trunks, etc., are yet 

 acutely conscious of discovery and will often escape, even when 

 they have not been disturbed, if observation is removed from them 

 for an instant. Other insects, on the contrary, are so sluggish that 

 they will permit themselves to he transfixed with a pin without 

 even moving. 



Fig. 20. — Tin- figure on the left is of Eumenes flavopicta, a long-waisted wasp 

 armed with a powerful sting, that en the right i- Syrphid Fly 



(Ceria sp.) which mimics the wasp. Beth insects occur eenti-mporaneously 

 in the same localities in Southern India. (Original.) 



The term "mimicry " is properly restricted to cases in which an 

 animal externally resembles another and biologically distinct kind 

 of animal. The resemblance may be extremely close and detailed 

 or it may be very rough and general ; it may occur in any stage ot 

 the lifehistory and may be produced by similar coloration, si 

 or action, or a combination of any or all of these, but the internal 

 and non-visible portions of the animal are never affected. The 

 animal whose external appearance is thus copied is called the 

 "model "and is generally distasteful to enemies in some way. as 

 by the possession of a sting or poisonous lute or nauseous taste or 

 smell. The animal which copies the external appearance of tin- 

 possessor of such noxious qualities is called the "mimic." When 

 the mimic is palatable or defenceless the mimicry is called " I 

 sian " mimicry ; but, in some cases, the mimic is equally distasteful 

 as its model, and such cases form what is called "Mullerian" 

 mimicry, both these cases (or theories) being called after the names 

 of the men who first clearly enunciated them. 



