184 THE UNIVERSITY SCIENCE BULLETIN. 



pond in late autumn and early spring. The migration from this pool 

 occurred in a very few days of warm spring weather. A few days after 

 taking mating pairs in numbers on April 29, the pool was almost de- 

 serted, scarcely one was to be found. An examination of the Meadow 

 pool, a quarter of a mile away, found them very abundant. Subsequent 

 surveys indicated that the latter pool was the breeding place of this bug, 

 for nymphs of this species swarmed the pool, forming, in fact, the domi- 

 nant type of insect life. Very few nymphs were ever taken in the 

 winter-quarters pool. The migration to deeper ponds and pools is 

 doubtless due to a desire to secure unfrozen waters. They have been 

 observed swimming slowly beneath the ice at the Field Station, Ithaca, 

 N. Y., in early February. 



Mating. The mating begins in early spring, and occurs in the water, 

 the male usually occupying a position to the left side of the female. The 

 pairs have been observed to remain in copula for two and three hours, 

 swimming about in the water, and the female even catching prey. Mat- 

 ing pairs may be taken over a considerable time, but about the last of 

 April they appear to be most active. 



Oviposition. In the matter of oviposition this species is the most in- 

 teresting of all the members of the genus in this country, for, as else- 

 where stated, it inserts its eggs in the tissues of plants. On plates VIII 

 and XXII are shown the photographs and the figures of the eggs in- 

 serted in moneywort and in water-soaked typha blades. One figure 

 shows two eggs inserted in a bit of water-soaked leaf of typha through 

 one aperture. As a rule, however, they are imbedded singly, wholly or 

 in part, depending upon the nature of the material serving for support. 

 The cephalic end of the egg is directed toward the opening. Females 

 deprived of vegetation of sufficient diameter to permit the insertion of 

 eggs (such as Chara) will hide them in mud and debris lodged in the 

 axils of the plant. In only two cases were they loosely affixed to the 

 chara. 



Incubation. The first eggs discovered were on May 12. They may 

 have been laid before this date, for they began hatching May 18. In 

 another aquarium some eggs were laid May 12, red eye spots were show- 

 ing June 2, and hatched by June 8. Another lot, laid between May 25 and 

 May 27, showed red eye spots June 11, and began hatching a few days 

 thereafter. Thus the egg stage of this species is comparatively long — 

 some two or three weeks, or even longer. 



HatoMng. The time of hatching in the laboratory began May 18. 

 The first nymphs were taken in nature during the first week in June. 



The hatching process has been outlined in connection with N. undulata, 

 but some special features that were observed in connection with this 

 species are worth noting. 



In attempting to study the behavior of newly hatched nymphs, the 

 eggs were kept under constant observation for many hours. One of the 

 striking facts of interest is the activity of the nymph within the egg 

 some hours before hatching. 



One evening when a number of eggs were expected to hatch they were 



