DEATH-FEIGNING IN RANATRA. 



S. J. HOLMES. 

 {From the Zoological Laboratory of the University of IVisconsin.') 



GENERAL CHARACTERISTICS OF THE DEATH FEINT. 



The instinct of feigning death is developed in Ranatra to an 

 unusual degree. If a Ranatra is picked out of the water it usually 

 becomes motionless, either at once, or after a few spasmodic 

 movements. Sometimes, however, the insect will not feign at 

 first, but kicks about with its second and third pairs of legs, at the 

 same time moving its anterior legs up and down so as to produce 

 its characteristic squeaking sound by rubbing the bases of these 

 appendages against the prothorax. When dropped on the table, 

 even while moving, Ranatra usually becomes quiet as soon as it 

 strikes the substratum. The attitude assumed is variable and 

 depends to a great extent upon the position of the legs when the 

 insect is dropped. The anterior legs are generally held close 

 together straight in front of the body. Sometimes the two hinder 

 pairs of legs are held straight backward close to the ventral side 

 of the abdomen where they lie in a depression on either side of the 

 median ventral carina. In this position the insect resembles a 

 straight stick and may very readily be mistaken for one. Fre- 

 quently both pairs of legs are bent forward and slightly dorsally. 

 All sorts of intermediate attitudes are assumed, and the legs on the 

 two sides are quite commonly held in different positions. This 

 variation in the position of the appendages is in marked contrast 

 to the definite and constant attitude which is assumed during the 

 death feigning of many other insects. 



When in the death feint, Ranatra lies motionless for a period 

 varying from a few minutes to several hours. Under ordinary 



