Vol. XXviii] ENTOMOLOGICAL NEWS. 2^1 



tained in the captured victims, their shells are cast aside and 

 the process repeated as opportunity affords. A careful exami- 

 nation of the field notes brings to light the fact that at the time 

 when Notonccta nymphs in their first and second instars were 

 in their greatest numbers, both in their spring and summer 

 generations, the waters were teeming with ostracods. In the 

 laboratory nymphs have been carried through the first four 

 stages on ostracods alone, but as a rule they were supplied 

 nymphal corixids in the later instars. The corixids have been 

 found very satisfactory for Bclostoma nymphs also. 



Adaptations to Aquatic Life. 

 Much has been written upon the adaptation of Notonecta to 

 an aquatic life. Brocher (1909) places them with the Nau- 

 corids, midway between the less modified Corixids and the 

 more greatly modified Nepids. He was considering the mat- 

 ter from the standpoint of respiration. Following some clever 

 experiments, in which he removed certain air retaining devices 

 of the body and closed, in turn, various spiracles, he concludes 

 that they inspire through the last abdominal pair of spiracles 

 and that the air retained about the body is for the most part ex- 

 pired air, liberated by the thoracic spiracles. Perhaps the first 

 note in this country representing a close observation of the res- 

 piration appeared in the American A'aturalist for 1887 and 

 was written by Professor Comstock. 



OVIPOSITION. 



A somewhat detailed account of the literature on the ovipo- 



sition of these insects was given in the discussion and in an 



annotated bibliography accompanying the paper "The Egg 



Laying Habits of a Back Swimmer, Bitcnoa jiiargaritacca" 



etc., bv the writer (1917). In this paper it was noted that 



Btietwa margaritacca places its eggs in the stems of plants. It 



may be stated that though TV. nndulata may sometimes abrade 



the surface, as noted by Bueno, the chitinous processes of the 



ovipositor are ill adapted to making any such deep incision as 



are made by B. margaritacca* Christine Essenberg (1915), 



*0n the other hand N. irrorata has a long ovipositor and inserts its 

 eggs wholly or in part in the stems of submerged plants. The writer 

 has had the opportunity just recently to study this species and finds 

 the eggs laid in the aquaria placed in incisions of the stems of money- 

 wort, etc. 



