Dec, 1921 Bulletin of the Brooklyn Entomological Society 133 



When the specimens were taken into the laboratory and placed 

 in warm water, they all revived. The bugs which were placed in 

 water at a temperature of 14° C. first began to show movement 

 after twenty minutes, while others placed in water at 20° required 

 only about half that time. The first movements observed were 

 spasmodic twitchings of the hind legs ; after about five minutes 

 more the bugs began to pass their legs over the hemelytra, thus 

 covering them with a film of water, and attempted to dive. 

 Flashing a strong light directly above the dishes containing the 

 bugs provoked strong reactions which persisted for perhaps half 

 a minute if the light remained on, but which died away almost 

 immediately if the light were merely flashed. At this time only 

 a few individuals were able to break down through the surface 

 film, the others being able merely to swim about in an erratic 

 manner over the top of the water. In all nearly forty minutes 

 had passed before any of the bugs were able to grasp pebbles or 

 plants in the shallow aquarium and so to remain submerged, and 

 only after an hour were they able to swim downward in a normal 

 manner. 



About one fifth of the boatmen died within twenty-four hours 

 after they had been revived in this manner; this may have been 

 due largely to shock from the sudden change of temperature. A 

 considerable number of individuals were still alive, however, 

 when I left Minneapolis some six weeks later. 



Experiments were begun at once to discover the manner in 

 which the Corixids get into the pockets in the ice, but they had 

 hardly been started when I was forced to abandon them for a time. 



When I returned to Minneapolis in the fall of 1919, I made 

 several trips to this pond and to the other ponds in the vicinity, 

 but it was not until November 17 that I obtained any individuals 

 of this species, though several species of Arctocorisa were plenti- 

 ful. On this date the pond was covered by about two inches of 

 ice, and the single fernale Cymatia seen was swimming rather 

 sluggishly in the open water near the bottom, where the water 

 was about fifteen inches deep. A week later a single male was 

 taken in the same place, and during December a few other indi- 

 viduals were also secured here. Meanwhile the other Corixids 



