STUDY ON THE DEATH-FEIGNING OF BELOSTOMA 37 



death could have been developed during the aquatic existence 

 among other Arthropods that are not insects? Andrews (i, p. 172) 

 in his work upon the breeding habits of the crayfish, Cambarus 

 affinis, observed that during sexual union the female feigns death 

 while in the water. " During the whole process of union, the 

 male is in a state of excitement while the female is quite the 

 reverse as far as could be judged. The action of the male in 

 turning and adjusting the female is greatly assisted by the 

 state of passivity simulating death that overtakes her soon 

 after being seized by the male. This inertia of the female extends 

 even to the respiratory movements, which seem absent in strong 

 contrast to the condition in the male." Andrews (i, p. 179) 

 furthermore found that the female crayfish shortly after egg- 

 laying lies motionless upon her back with the limbs stifHy 

 extended and seems dead unless the- strongly bent abdomen 

 suggests muscular contraction. Holmes (9, p. 288-292) noticed 

 in a number of amphipods that the female, as soon as it is 

 seized by the male, curls up, her thoracic legs are drawn up 

 and the abdomen is held strongly flexed; the whole body in 

 short assumes as compact a form as possible. The female, 

 while being carried about, keeps remarkably impassive. " Males 

 which were mutilated so that they could not resist seizure 

 were carried about as if they were members of the other 

 sex. The mutilated males were more active than the females 

 are under the same conditions, and did not assume the bodily 

 attitude, * * * " i^ Cyclops, Holmes (10, p. 315) again finds 

 that " the females tend to remain quiet in a condition some- 

 what resembling the death feint while being seized by the males." 

 Among these Crustacea, the death feint of the females in the 

 water may possibly be a sexual modification which has been 

 secondarily acquired. 



Among the aquatic Hemiptera, the death feint may have 

 arisen out of positively thigmotactic propensities which are 

 manifested to such a marked degree by various members of 

 the families Belostomidae and Nepidae. In a previotis paper,* 

 attention has already been called to the fact that Belostoma and 

 Nepa as well as other closely related aquatic Hemiptera cluster 

 together to form groups whenever possible, which is probably 

 a manifestation of their positively thigmotatic response. Belos- 



1 Joum. N. Y. Ent. Soc. XIX., No. 2, pp. 99-108. 



