402 CHRISTINE ESSENBERG 



surface or on plants. They show no particular choice in the 

 selection of food, eating any dead or living animal matter. If 

 nothing is obtainab'e, they can live without food for weeks 

 or months. They are specially given to the cleaning habit 

 and may be engaged in this process for hours in succession. 

 They are prone to feign death and may be artificially stimu- 

 lated to do so several times in succession. They are positively 

 phototactic. 



Gerris remiges is positively thigmotactic, hence, usually found 

 in groups or piles beneath rubbish and rocks. The insects also 

 crowd together on the surface of the water. They are positively 

 rheotactic and negative y geotactic. 



They seem to have some sense of smell. Their sense of 

 hearing is not well developed, but they detect a sudden jar, 

 such as the slamming of a door, or drumming on the edge of 

 the aquarium, etc. 



The sense of sight is keenly developed, the insects detecting 

 a moving object or a shadow very quickly. 



In considering the economic aspect,' these insects may be 

 useful because of their contribution to the reduction of the 

 number of mosquitoes which lay their eggs on the surface of 

 the water, also because of their destroying the emerging young 

 mosquito. 



LITERATURE CITED 



Bueno, J. R. de la Torre. The Gerridae of the Atlantic States. Trans. Amer. 



1911. Ent. Soc, 37, 243-252. 



1911. On the Aquatic and Semi-aquatic Hemiptera Collected by Professor 

 T. S. Hine in Guatemala. Ohio Naturalist, 8, 370-382. 

 Douglas, J. W. Notes on Gerris thoracica. Entom. Mo. Mag., 16. 



1870. 

 Holmes, S. J. Death- feigning in Ranatra. Journ. Comp. Neurol, and Psvchol., 



1906. 16, 200-216. 

 Kirkaldy, C. W. A New Species of Gerris. Entom. News, 22, 246. 



1911. 

 Miall, L. C. Natural History of Aquatic Insects. Macmillan and Co., London. 



1895. 

 Severin, H. P. and Severin, H. C. An Experimental Study on the Death-feigning 

 of Belostoma (Zaitha aucct.) fiumineum Say and Nepa apiculata 

 Uhler. Behavior Monograph, 1, 11-85. 



