Hungerford: The Toad Bug. 147 



neath tlie dirt in cloudy weather and remain tlius many liours. This 

 habit may be their method of maintaining their geographical posi- 

 tion in time of flood. I have observed broad, sandy, barren flats 

 where toad bugs lived become inundated by rapid currents of 

 water for a few hours; nevertheless, when the water receded and 

 the sun came again, here were the bugs as before. There were 

 neither vegetation nor sizable stones for their anchorage, so I sup- 

 pose they "dug in." They hop about with considerable alacrity 

 when alarmed (one first instar nymph jumped ten inches). They 

 pounce upon their prey, which appears to consist of almost any 

 sort of . insect they can capture, from a grouse locust (tettix) to a 

 lacebug. 



MATING. 



There is considerable sexual dimorphism with the toad bug. The 

 abdomen of the male is strongly asymmetrical, as is also the case in 

 the male Corixidse. Figures illustrating this are shown on plates IX 

 and XXXII of Science Bulletin, vol. XL At that time no ob- 

 servations had been recorded on the mating. The male mounts the 

 female, grasping her with the middle pair of legs, the first pair 

 flexed beneath him, and the abdomen somewhat to the left side. 

 This decided and invariable position to the left is due, of course, 

 to the asymmetrical structure of the male genitalia. The fre- 

 quency and duration of copulation of various pairs under obser- 

 vation is given herewith. 



