LIFE HISTORY AND HABITS OF POLISTES MBTRICUS 279 



Although much time was spent with the wasps nearly every 

 day, it was a long time before the mot her was observed in 

 the act of laying. When the weather was nice she laid an 

 egg nearly every day, as was observed by careful note of 

 all empty cells. In cool weather she would sometimes miss a 

 day, or even two or three. She laid on the 11th and 12th of 

 June, then again on the 14th and 15th. Only one more egg 

 was laid until the 20th. Apparently the wasp was very sensi- 

 tive to weather conditions. 



Finally by noting the conditions at the various times of 

 my visits it was determined that the eggs were laid in the 

 morning between eight and eleven o'clock. Accordingly on 

 the last day of June, even though I had an engagement in a 

 distant city, I determined to see the eg(<: laid before leaving. 

 I took up my watch shortly after eight o'clock and waited 

 rather impatiently. The mother was rather sluggish and there 

 was little action to keep up interest for nearly two hours, 

 before she began preparing for her day's work. She would 

 remain entirely motionless for many minutes at a time, then 

 she would look into a few cells, and again become quiet. Pinal 

 ly about ten-thirty a. m., she flew away and was gone but a 

 few minutes. On her return she began looking about in search 

 of an empty cell. Finding one by pushing her head deeply 

 into it, she doubled herself very shortly, and reversed her 

 position, placing her abdomen into the same cell. She then 

 remained very quiet with her head toward the center of the 

 comb for several minutes. At last she moved out and again 

 put her head in to see that the newly laid vgg was in its 

 proper place. Afterward she again became quiet for some 

 time. Although I came near missing the train as a result of 

 the long wait, I felt that the time had been well spent, and 

 thereafter had no further difficulty in observing the egg lay- 

 ing as frequently as I wished. 



A number of eggs were marked to ascertain the period re- 

 quired for hatching. Most of them hatched in just eighteen 

 days. When the weather warmed a bit some hatched in six- 

 teen days. Since the weather was cool and the temperature 

 so much below normal probably this is longer than the normal 

 period. A number of those observed spinning their cocoons 

 spent twenty-three days in the pupal state. A few individuals 

 required twenty-five days to complete the transformation. 



