302 WASP STUDIES AFIELD 



dropping them a few inches from the burrow. The accom- 

 panying figure (fig. 56) illustrates a number of these 

 pellets, which nicely show the marks left by the manipula- 

 tion of the mandibles. 



We suspected that the dirt taken out of the hole was 

 applied to the chimney, but we were perplexed that the 

 wasp should apply part of her excavated clay to the tur- 

 ret, and, with the same careful precision, carry out and 

 discard other pellets. Finally, near the end of the season, 

 on September 16, we got a clue to the answer to the ques- 

 tion. We found a turret which seemed incomplete ; it went 

 straight up for one-third inch and had no curve or hori- 

 zontal portion. The wasp was carrying out moist pellets ; 

 but instead of applying them to the turret she was taking 

 them out a few inches from the hole and discarding them. 

 When we returned the next afternoon the turret stood at 

 precisely the height at which we had left it. The wasp 

 was no longer carrying out pellets, but she emerged every 

 few minutes and played about the mouth of the chimney. 

 Imagine our surprise when closer scrutiny revealed to us 

 that she was at these times biting off a mouthful of clay 

 from the margin of the chimney, after having moistened 

 the spot with water just as she does in digging her hole, 

 and carrying it down into the burrow ! Her work was 

 methodical and accurate really charming to see. She 

 would come up to the top of the turret, spread a drop of 

 water, bite off and knead together a large mouthful and 

 carry it down, head first, into the hole, and come up in a 

 moment to repeat the performance precisely. The fact that 

 she moistened only enough clay at each trip to make the 

 desired chunk indicates again that she must carry the supply 

 of water in some other way than in the mouth; perhaps 

 deep down in her throat. When her supply of water v/as 

 exhausted, she flew away for more. Returning after a 



