Dec, 1921 Bulletin of the Brooklyn Entomological Society 131 



ECOLOGICAL NOTES ON CYMATIA AMERICANA 

 (CORIXIDAE, HEMIPTERA). 



By Roland F. Hussey, Forest Hills, Mass. 



(Contribution from the Entomological Laboratory of the Bussey 

 Institution, Harvard University, No. 189, and from the Ento- 

 mological Laboratories of the University of Minnesota.) 



I. A Remarkable Mode of Hibernation. 



The hibernation of the waterbugs is a peculiarly interesting 

 subject, and one about which comparatively little is known as 

 yet. Certain species, notably the surface-dwelling forms, pass 

 the winter under logs, mats of grass, and other debris at the mar- 

 gins of the ponds and streams on which they are found during the 

 summer. It seems that they must certainly endure temperatures 

 far below the freezing point, especially in the more northern parts 

 of their ranges. The truly aquatic forms, living in the open 

 water, are commonly reported to hibernate deep in the mud at the 

 bottom of the ponds; and here the temperature probably never 

 goes below the freezing point in normal winters. 



To these two types of hibernation may be added a third, to be 

 described below, which is truly unique: here the bugs pass the 

 winter sealed in small cavities in the ice which covers the ponds 

 in which they dwell in summer. This peculiar mode of wintering 

 was observed at a small pond at the northeast corner of the Uni- 

 versity Golf Links, a little over half a mile north of the Univer- 

 sity of Minnesota Farm School in St. Paul. This pond is roughly 

 trapezoidal, about 75 yards long and 40 yards wide at its widest 

 point. A roadway has been built through the pond, cutting off a 

 small part near the south end. The bottom is very soft mud, 

 and, especially in the larger part, the pond has only a very scant 

 growth of, aquatic vegetation. 



Collections made here in September and October of 1918 

 showed the hemipterous fauna of these ponds to be fairly typical 

 of the north-central United States. Various species of Corixidse 

 were found to be the most numerous of the waterbugs, and most 



