270 ENTOMOLOGICAL NEWS. [Juiie, '17 



writer has enlarged upon this point, but they also feed quite 

 largely upon ostracods and similar organisms, especially in 

 their younger stages as has been previously pointed out by 

 the writer.* He began his attempts at rearing by using mos- 

 quito wrigglers as recommended by Delcourt, but met with 

 indifferent success, perhaps because he did not secure t"hem in 

 proper sizes. It was soon discovered that ostracods made an 

 excellent fare and afforded a constant supply. A large aquar- 

 ium was. teeming with them, from which they were transferred 

 by means of a pipette to the small petri dishes in which the 

 notonectid nymphs were isolated. It is interesting to watch the 

 nymphs feed upon these little bivalves. The capture and 

 consumption may be watched under the binocular with ease 

 for the prey is held against the venter, which is upper-most 

 as shown by the drawing, PI. XIX, fig. 8. 



The little notonectid is not prone to carry on an extended 

 chase, doubtless aware that success is more surely attained by 

 waiting until the prey comes within striking distance, than by 

 sustained effort. 



Thus it rests suspended from the surface film with the row- 

 ing legs poised well forward of right angles to the body, ready 

 for a sudden attack. At last an unsuspecting ostracod comes 

 gliding over the bottom of the petri below, a sudden dart, dodge 

 and a turn and notonecta returns to its former position on its 

 back, tip of the abdomen at the surface film and the body 

 sloping head downward at its customary angle, but now em- 

 bracing the luckless bivalve with both fore legs. With the 

 armored prey, held prisoner upon the coxae of the fore legs, it 

 turns it about to find a vulnerable point in which to jab its 

 stylets — at last success is attained, the valves open and do not 

 close again for the nymphal backswimmer feeds. Though 

 partaking of the contents of this ostracod and both fore legs 

 busy retaining perhaps as many as two others, gathered since 

 the feeding began and which are striving to escape, this greedy 

 fellow dives again and again at other ostracods that pass near 

 by. Finally, having exhausted the supply of nutriment con- 



*Science N. S. Vol. XI^V, No. 1162, Page 336, April 6, 1917. 



