20 HENRY H. P. SEVERIN AND HARRY C. SEVERIN 



It is evident from these experiments that the duration of 

 the death feint diminished when the insect is taken from water 

 at a low temperature and exposed to a temperature of the atmos- 

 phere lower than 12° C. This result differs from Fabre's (6, 

 pp. 23-4) work on the Buprestid, Capnodis tenebrionis, Lin. and 

 Holme's (12, pp. 207-8) investigation on Ranatra, for both of 

 these naturalists find that cold increases the duration of the 

 death feint to a very marked degree. 



It occurred to us that the warm stimulus of one's fingers prob- 

 ably had some effect upon the specimens and a number of the 

 experiments under table V were repeated, care being exercised 

 not to touch the insects with our fingers but to seize them with 

 a pair of forceps and cause them to feign by stroking them with 

 a camel's hair brush. But we noticed no marked change upon 

 the duration of the death feint. 



It is worthy of mention that in those experiments in which 

 the temperature of the water was 10° C. or lower, many Belos- 

 tomas could only be induced to assume that death-feigning 

 attitude in which the legs are folded against the ventral surface 

 of the body (fig. i). Probably this condition was due, in great 

 measure, to the numbness produced by the cold. Belostomas, 

 however, were often raked or scooped out of the water in the 

 autumn or taken out of an aquarium when the temperature of 

 the water was considerably higher than in these experiments 

 and yet the bugs often assumed this death-feigning posture; 

 these insects, however, could always be induced to assume the 

 other characteristic death -feigning attitude (fig. 2). 



When Nepas, on the other hand, are exposed to a low temper- 

 ature, the insects remain in the death feint considerably longer 

 than when they are made to feign in a higher temperature (table 

 IV). Two experiments were performed, in each of which care 

 was taken to expose each lot of Nepas for three or four hours 

 to the temperature at which they were afterwards made to feign. 

 The averages of the first death feint in ten specimens in the two 

 experiments were as follows : 



Experiment I. 

 Nepas kept at 13° C, 21.9 minutes. 



Experiment II. 

 Nepas kept at 9° to 10° C, 33.1 minutes. 



