88 Bulletin American Museum of Natural History. [Vol. XXII, 



Experiment 48. Aug. 27, 12 m., a tine female Polyergus was placed in a nest 

 with 4 large schaufussi workers and about 100 worker cocoons, all taken from 

 a large wild colon3^ The female at once killed a worker that she encountered 

 while running about the nest, and a few moments later dispatched two others 

 in quick succession. The single remaining worker ran about with a young 

 larva in its mandibles, trying to escape from the female. The latter returned 

 again and again to the murdered workers and thrust her mandibles through their 

 bodies. She paid no attention to the cocoons. By 9 p. m. she had killed the 

 last surviving worker. During the two following days she ran about the nest 

 or rested for long periods on the moist sponge, but never gave the least heed to 

 the cocoons which lay scattered about the nest as they had been dropped by 

 the demoralized workers. At 6 p.m., Aug. 29, she was removed from the nest. 



In the two preceding experiments the Polyergus females were very 

 aggressive and showed much of the insensate eagerness to kill alien 

 workers so characteristic of the Polyergus workers. Neither in these 

 nor in the succeeding experiments was a female ever seen to touch 

 a cocoon with her mandibles, though often compelled to feel them 

 with her antennae and to walk over them while moving about the 

 nest. In the two following experiments the behavior of the female 

 Polyergus presents still another aspect, as passive as the preceding 

 was agressive. 



Experiment 4Q. Aug. 27, 11.30 a.m. A fine Polyergus female, placed in a 

 nest with 14 large schaufussi workers and several cocoons, was soon seized by a 

 worker. She pierced its cranium with her mandibles and compelled it to re- 

 lease its ho d. While she was extricating herself from the jaws of this worker 

 she was attacked by another, but did not offer to defend herself. Some of 

 them pulled her about by the legs or antennae while others fired volleys of formic 

 acid into her face. She eventually escaped and without any signs of fear or 

 resentment ascended the pile of cocoons. Here the workers seized her again 

 and dragged her away. She drew her limbs up against her body and remained 

 in a quiescent, pupal attitude while they tried to pierce her shining integument 

 with their sharp mandibles. At noon she was still being dragged about pas- 

 sively. At 1.35 P.M. she was attacked simultaneously by 5 workers. By 6 

 P.M. they had succeeded in injuring her and she was so weak that she was 

 removed from the nest. 



Experiment §0. Aug. 27, 6.20 p.m. Another Polyergus female was placed 

 in the nest employed in the last experiment, which still contained 13 schaufussi 

 workers. There was a great commotion among the latter as they fled with 

 their cocoons. She was seized by one of the workers but did not retaliate. 

 She was almost at once released and went to rest in a corner. Aug. 28, 7 a.m., 

 she was still alive, quietly resting on the moist sponge at some distance from 

 the workers and their brood. At 9.15 p.m. she was walking about the nest. 

 Whenever she passed workers they threatened her with half-open mandibles 

 but went no further. She was not in the least aggressive. Aug. 29, 7 a.m., 

 matters were in statu quo. A worker came up and pulled the female's leg, but 



