STUDY ON THE DEATH-FEIGNING OF BELOSTOMA 25 



A glance at tables I and II shows that the first death feint 

 under normal conditions is usually shorter than the next three 

 or four successive feints. For this reason, the two preceding 

 experiments were repeated; each specimen w^as taken from 

 water at i8° C. and caused to feign five successive times at the 

 temperature of the atmosphere at 21° to 22° C. The averages 

 of the first five successive death feints in ten Belostomas kept 

 under the stationary lamp was as follows: 6, 7.2, 11, 14-8, 

 16.2, 16.4, 22.9, 24.8, 25.2 and 25.5 minutes, the total average 

 being 17 minutes. The averages of the first five successive 

 death feints in eighteen specimens kept under the swaying electric 

 lamp was: 2, 4.3, 5,7, 6.2, 7.7, 8.8, 9.8, 9.9, 12.8, 14, 14.4, 14.4, 

 14.6, 15.5, 15.7, 17.2, 21.2 and 23.2 minutes, the total average 

 being 12 minutes. The difference in the total averages of the 

 first set of experiments is 6 minutes and of the second set of 

 experiments, 5 minutes. Evidently Belostomas are aroused from 

 their death feint more quickly under a swaying light than if 

 it is kept stationary and this is true whether the average of 

 the first death feints or the first five successive feints of a large 

 number of specimens are taken. 



In similar experiments wdth Nepa, all the insects were first 

 exposed for three hours to the light of a stationary lamp about 

 eighteen inches away. Ten Nepas were used in each experiment. 

 The averages of the first death feints are as follows: 



Temperature of atmosphere 18° to 19° C. 

 Under stationary light. Under moving light. 



12.8 minutes. 7.3 minutes. 



15.9 " 10.9 



17. Reactions to light previous to and after coming out of the 

 death feint: Nepa, when feigning death w^hile lying on its ven- 

 tral surface under a moving light, soon responds to the move- 

 ments of the lamp by corresponding head-movements. Thus, if 

 the light is moved back and forth over the specimen laterally, 

 the head is turned each time so that both eyes receive some 

 illumination. If the lamp is moved over the long axis of the 

 body, the head again responds, lowering while the light is being 

 placed in front of the individual and tilting upward when in 

 back of it. If the light is moved in a circle, the head also rotates 

 in a circle. These head movements are at first slight, and either 

 the side to side or the up and down movements will be given 



