156 Journal New York Entomological Society. [Vol. xm. 



cut. The general characters given will serve to separate it in all cases 

 of doubt. There are in my collection some specimens in which the 

 hemelytrre are stained a peculiar brownish black from the water, to a 

 greater or less degree. In the national museum collection, there is a 

 remarkably small specimen from southern California. It approaches 

 in form and size JV. undulata, var. rirescens, from which, however, it 

 can be readily separated by the notocephalic structure. It is only 8 

 mm. long and 2.8 mm. wide. 



Prof. Uhler, according to his letters to Mr. Kirkaldy, is of the 

 opinion that this species, JV. undulata Say, and JV. indica L. are mere 

 varieties. But on the other hand, I have in my collection long series 

 of both JV. undulata and JV. variabilis taken in this locality, and have 

 never met with an intermediate form among them. On the contrary, 

 I have found them always very constant to type. Then again, where- 

 ever JV. undulata was found abundantly, JV. variabilis was absent ; 

 and where I found large numbers of JV. variabilis, I have taken not 

 more than three or four A r . undulata altogether. In my opinion, 

 Notonecta variabilis Fieber is a good species, entirely distinct from 

 Notonecta undulata Say. 



The life-history of this water-bug, in common with all others of 

 the family, is unknown. Breeding experiments have given me the 

 ovum, which is very similar to that of N. undulata, except that it is 

 naturally smaller, and perhaps a little more slender in proportion. I 

 can also hazard a guess as to the number of stages, from field material 

 and give approximately the period of embryonal development. Ovi- 

 position begins early in the spring, and continues thereafter, how late, 

 I am unable to say. The ovum is deposited in a similar manner to 

 that of N. undulata, mentioned previously, and the period of incuba- 

 tion is some 22 days on an average ; this varies according to the con- 

 ditions and temperature. Females in my aquaria have deposited some 

 30 ova each, but this cannot be an exact figure. The bugs arrive at 

 maturity in the late July or early August, as shown by captures of 

 recently transformed individuals. From nymphs taken at the same 

 place on same date, it would appear that there are five nymphal 

 instars, or perhaps, six. The adults pass the winter concealed in the 

 mud at the bottom of the pools they frequent, emerge in the spring as 

 soon as the ice is melted, and immediately begin to breed. 



