122 Journal New York Entomological Society. [VoL xxv. 



the flocculent deposits at the bottom of the pool they gather the 

 organic ooze and some of the population both plant and animal that 

 it contains. The living organisms consumed in their feeding range 

 from the filamentous algre to rotifers: and oligochaete worms. 



They in turn are preyed upon by many aquatic carnivores and 

 may be looked upon as members of the producing class. 



Their eggs appear a little earlier in the spring than those of 

 Notonecta. The incubation period of the egg covers a week, and 

 each of the five nymphal instars requires approximately a like time,^ 

 thus bringing them to the adult stage in some six weeks. While 

 they may be found many times in all stages of development, the 

 definite broods are not difiicult to follow in nature, and in proper 

 waters, with an absence of a dominating predatory population, they 

 thrive in astonishing numbers. 



Of all the true water bugs, they alone have been found the forage 

 of any of the fishes. May they in some small measure at least 

 ameliorate the unfortunate reputation of the rest of the water bugs, 

 whose predatory and cannabilistic tendencies have been many times 

 recorded. 



EXPLANATION OF PLATE IX. 



Fig. I. Egg of the corixid species here considered. 



Fig. 2. Adult corixid, Artocorixa alternata? 



Fig. 3. Egg of a smaller undetermined species. 



Fig. 4. First instar nymph. 



Fig. 5. Second instar nymph. 



Fig. 6. Tarsus and claws of hind leg of first instar. 



Fig. 7. Third instar. Note the fringe of black hairs on the wing pads. 



Fig. 8. Egg shell after hatching, showing the characteristic rupturing of 



the egg for the egress of the nymph. 



Fig. 9. Fourth instar nymph. 



Fig. 10. Front leg of late fifth instar nymph showing the tibia and tarsus 

 of the adult within the terminal nymphal segment. 



Fig. II. Fifth instar nymph. 



Fig. 12. The foreleg of the adult male. 



Fig. 13. Ventral view of abdomen of female. 



Fig. 14. Antenna of third instar nymph. 



Fig. 15. Antenna of late fifth instar, showing the three distal segments of 

 the adult in the terminal nymphal segment. 



Fig. 16. Antenna of adult. 



Fig. 17. Ventral view of abdomen of male, showing the peculiar asymmetry 

 of the segments. 



9 The last nymphal instar often requires a longer time. 



