hungerford: aquatic hemiptera. 185 



watched closely for hours. One attracted attention especially because 

 the embryo was seen to be moving within its shell. One observation 

 found it in the position shown in the drawing on plate XXII, fig. 3. A 

 little later the embryo had rotated upon its longitudinal axis so that the 

 eye spot on the right side in the drawing was on top. Fifteen minutes 

 later the right eye had continued its rotation until it held the position 

 on the left side. In ten minutes more it was in its original position 

 again. This movement of the embryo, as followed by the pink eye spots, 

 continued at intervals for several hours. Emergence was expected at 

 any moment, but did not take place for many hours after the writer 

 had despaired of seeing the event take place. 



Number of histars. There are five instars, which after the first are 

 much alike, and to be distinguished by the dark markings on the sides 

 of the abdomen. 



Maturity. The overwintering adults mate and begin egg laying in 

 May. The first nymphs in nature were noted in the first week in June. 

 By the last of June they were in all stages up to the fourth. On July 

 1, they were coming into the fifth instar at the Meadow pool, where the 

 nymphs were most abundant. Frequent visits were made to this pool 

 at Ringwood to observe the first adults of the new generation. While 

 there were overwintering adults alive in the laboratory, careful collect- 

 ing showed they had disappeared from this pool, so great interest was 

 aroused in the behavior of this species in this Meadow pool. On July 7 

 there were many fifth instar forms, but no adults. I brought some of 

 these to the laboratory and placed them in an aquarium, where the first 

 adult came forth July 18. The next day a trip was made to Ringwood, 

 and the Meadow pool contained many newly emerged N. irrorata adults ! 

 Beautiful fellows they were, too, with their velvety, richly-colored backs! 

 There is no mistaking these fellows for the older generation. Now, the 

 next step was to determine if these fellows would bring forth another 

 generation. Adults were brought to the laboratory and confined in an 

 aquarium. The writer left them in the care of a friend, who reported 

 that no eggs were deposited, and some were alive on October 22, when 

 the experiment was abandoned. Only three or four individuals were 

 followed, and the sex of these not fully established, so little data can 

 be given concerning any evidence of a second generation of this species 

 in New York state. 



LABORATORY RE-\RING. 



One series will indicate the various stages and the duration of time 

 required for each. On April 20, three N. irrorata taken at Six Mile 

 pool were placed in a glass battery jar with some fresh sprigs of Money- 

 wort taken from above the water line. On May 12 eggs were discovered 

 imbedded in the stems of the plant. These began to hatch on May 18. 

 Some of these changed to second instar June 1, to the third June 9, and 

 to the fourth June 20, to the fifth July 1, and to the adult the middle of 

 July. These nymphs had been isolated in small stenders and jelly glasses 

 and fed Cyclops and Ostracods. The first-instar fellows were seen to 

 eat Ostracods nearly as large as themselves. When first hatched the 



