376 WILLIAM MORTON WHEELER 



pressly stated, it is clear from Ainslee's vivid description, that 

 A. taurulus preys on the workers of the Pogonomyrmex. As 

 will be seen from the following account, our eastern A. frigidus, 

 though it also provisions its nests with ants, selects only the 

 fertile females, or queens. 



My observations on frigidus were made in the Blue Hills, 

 near Boston, during July and August. The wasps were found 

 to be at the height of their activities from July 26 to August 

 16. By the end of the latter month all the wasps had disap- 

 peared and the nests had been effaced by recent heavy showers. 

 Like the species of Bembex, frigidus nests in colonies. Several 

 of these were located, but observations were confined to three, 

 which happened to be within easy reach from Boston. They 

 were situated in the ravine that separates Great Blue Hill from 

 the adjacent portion of the range, two of "them being in the 

 stony and sandy trail passing through Wild Cat Notch, the 

 other on Administration Road. Each colony covered several 

 square yards of territory and comprised from about 30 to 60 

 nests, the entrances of which were often within an inch or two 

 of one another. In two of the colonies the nests were inter- 

 spersed with the burrows of large Crabronid wasps and of 

 Cicindelid larvae. The wasps prefer to make their burrows on 

 slightly sloping surfaces. The opening, a little more than a 

 quarter of an inch in diameter, is semi-circular and lies in front 

 of a little pile of earth that has been thrown out by the burrow- 

 ing insect. The wasp spends much time, especially during the 

 morning hours or on cloudy days, sitting in her burrow and 

 looking out with her conspicuous black face, marked with three 

 vertical yellow bands like exclamation points. As the heat of 

 the day increases, however, she becomes more active and either 

 does more or less excavating in the nest, kicking the earth out 

 backwards from the entrance to a distance of a few inches, or 

 goes off foraging for her prey. In all of this behavior she ex- 

 hibits a striking resemblance to Bembex. 



The burrow descends obliquely and abruptly to a depth of 

 only six to eight inches, where it terminates in a small cell. 

 There are also two or three other cells, but it was found impos- 

 sible to determine their precise relations to the other portions 

 of the nest, owing to the very dry and crumbling condition of 

 the soil and to the fact that each cell is closed off from the main 



