STUDY ON THE DEATH-FEIGNING OF BELOSTOMA 41 



6. Dryness decreases and moisture increases the duration of 

 the death feint in Belostoma. 



7. The duration of the death feint diminishes when Belostoma 

 is placed upon the surface film or below the surface of the water. 



8. The duration of the death feint diminishes when Belostoma 

 and Nepa are exposed to a high temperature of the atmosphere. 

 The death feint decreases in Belostoma, but increases in Nepa 

 when these insects are caused to feign at a low temperature of 

 the atmosphere. In Belostoma, the death feint diminishes when 

 the transition occurs from water at a low temperature to the 

 temperature of the atmosphere lower than 12° C. The duration 

 of the death feint decreases when Belostoma and Nepa are 

 taken from water at a high temperature and exposed to a low 

 temperature of the atmosphere. 



9. The death feint diminishes when Belostoma is exposed to 

 sunlight. In order to determine the direct effect of light alone 

 on the death feint, an artificial light was used. It was found 

 that Belostoma and Nepa are . aroused more quickly under a 

 bright than under a much dimmer light, and under a swaying 

 light than under a stationary light. Previous subjection to 

 darkness, and a sudden transfer into a bright light decreases 

 the duration of the death feint in Nepa considerably. 



10. Decapitation of a feigning Belostoma usually brings the 

 water-bug out of the death feint. Although the majority of 

 specimens with the supra-oesophageal ganglion removed could 

 be induced to assume the death-feigning posture, still that extreme 

 muscular tension under which the intact insect labors while in 

 the death feint w^as very much weakened and of short duration 

 and often even entirely absent. With those decapitated Belos- 

 tomas that assumed the death-feigning attitude, a weakened 

 tetanic condition of the muscles could be induced by gently 

 stroking the abdomen with a camel's hair brush, but the instant 

 the stroking ended the legs would sprawl apart and become lax. 

 One is inclined to believe that the death-feigning attitude is in- 

 duced by the usual method of handling the insect while eliciting 

 the death feint and that the weak contraction of the leg muscles 

 is a reflex in response to a contact stimulus , rather than that the 

 tetanic condition was brought about through a death feint. 

 It may be possible, however, that there is a marked diminution 

 of the death feint due " to the heightened irritability which 



