280 IOWA ACADEMY OF SCIENCE 



Two years before, some under observation completed this stage 

 in only fifteen days according to my notes, which indicates 

 that weather greatly influences the length of the various peri- 

 ods of development. 



"When the larvae had completed their growth, the spinning 

 of the cocoons was an interesting observation. It was on the 

 24th of June that the first two completed this performance. 

 Although the operation was not timed, probably not more 

 than an hour was required to spin the cocoon. The silk was 

 very filmy and so fine that a single strand could hardly be 

 seen with the naked eye. During the spinning the larvae 

 moved their heads back and forth, round and round, constant- 

 ly adding to the web. At first it was very thin and the in- 

 mate of the cell could plainly be seen at work through the thin 

 network. It gradually thickened, until the spinner w r as en- 

 tirely hidden from view, although the movement continued 

 for some time after the covering became opaque. 



Thinking to see something of the transformation a small 

 hole was cut in the top of one of the cocoons. The day fol- 

 lowing the cell was found to have been emptied and a new 

 egg placed therein. Apparently this change is not for the 

 eyes of man to see. 



As the days passed, the experiment of feeding the larva? 

 was continued. Mosquitoes being plentiful in the weeds near 

 at hand, they were caught daily and fed to the larva 1 . At 

 times the mother would take them away and eat them her- 

 self. At other times she would feed them to the youngsters 

 as already described. More often she would resent the in- 

 terference with her family affairs and toss the dead mos- 

 quito contemptuously away. At times wiien she became nerv- 

 ous or angry she would cut the tops of some of her paper 

 cells. Snip, snip she would cut away using her mandibles 

 like a pair of scissors. Although on such occasions she was 

 watched closely, she was not again seen to feed the paper to 

 her offspring as in the one instance already described. "When 

 she was offered small caterpillars in place of the mosquitoes, 

 she would accept them readily, roll them up into a ball and 

 knead it vigorously and then feed the larvae. 



On warm days polistes was very active. Between her build- 

 ing and the feeding of the larva? she was busy, indeed. After 



