AQUATIC INSECTS IX NEW YORK STATE 295 



they can carry a supply of air with them. Many water beetles 

 carry a supply of air under their elytra; others carry it on the 

 ventral side of the abdomen and thorax. This supply is re- 

 plenished and purified by the insect going to the surface of the 

 pond from time to time. By the larvae, pupae, and adults 

 of the Donaciinae, neither of the above methods is in use. In 

 the following pages the method these insects pursue for 

 obtaining a supply of air will be described. The account is 

 based on studies made on the life history of D o n a c i a p a 1 - 

 m a t a , which occurs abundantly throughout the summer at 

 Ithaca. 



Specimens of Donacia palmata were found most 

 plentiful on the plants of the yellow pond lilies growing in the 

 lagoon extending from the south side of Fall creek just above 

 where it empties into Cayuga lake. It is known as the White 

 Lily pond, because it is the only place where this plant is found 

 at the head of the lake. This lagoon extends off from the main 

 stream in a rather sinuous course for about 200 yards. At no 

 place is the water more than 3 feet deep. The bottom consists 

 of soft loamy ooze about 2 feet deep. It is in this ooze that 

 the underground stems of the yellow pond lily grow. In order 

 to obtain the stems containing larvae, it was necessary to get 

 into the water and pull them up from the bottom of th(.^ ooze. 

 Along the banks of the lagoon there w^as a luxuriant growth 

 of Sagittaria, Pontederia, Polygonum sagittatum, 

 Scirpus, and Typha. It was along here that the larvae 

 and pupae of Donacia a e q u a 1 i s and H a e m o u i a 

 n i g r i c o r n i s were obtained. The conditions existing are 

 well shown by plate 20, where the luxuriant shore growth is 

 represented in the foreground, while the water just beyond is 

 almost hidden by the leaves of the yellow pond lilies floating 

 on its surface. 



In the early summer, while the water is deep or the stems are 

 not long enough to raise their leaves above the surface of the 

 water, the eggs are laid on the underside of the leaves of the 

 large jellow pond lily, Nymphaea advena. Growing in 



