30 Trans. Acad, of St. Louis 



goodly numbers, and by July 1 they were at the height 

 of their abundance. From that date on, their numbers 

 did not increase, but with the disappearance of the males 

 a decrease was soon apparent. The appearance of the 

 same colony has been previously recorded for June 16 in 

 1914: and July 4 in 1915 and June 27 in 1918. In 1920 

 they emerged on July 2, in even greater numbers than 

 in previous years, and the increased numbers made the 

 dance seem even more riotous than usual. This cele- 

 bration was confined strictly to the morning hours, 9 to 

 11. We were long in doubt whether the young wasps 

 emerged from their cells deep underground by following 

 the old channels made by the mother and refilled, or by 

 cutting new ones straight to the surface above them. 

 More recent investigation has shown that some follow 

 one route, some the other, and we have so far been unable 

 to find any factors which would determine their choice 

 in this matter. 



While these Bembix generally choose their own site 

 for a new burrow when the time arrives for them to give 

 serious attention to nidification, yet we have seen several 

 instances of the newly-emerged insect turning around 

 and utilizing the old slanting channel of its emergence, 

 which in turn was the channel dug by its mother and 

 filled in the previous season. 



While this species feed Dipterous insects to her young, 

 the mothers have been seen a number of times feeding on 

 the nectar of the iron-weed flowers. 



Cerceris fumipennis. Wickes, Mo., July 17, 1918. Roam- 

 ing at twilight down a little frequented road I chanced 

 to find in the middle of the path a pretty mound of soil 

 with an entrance in the center. The burrow was un- 

 covered. The nest was excavated; a wasp of the above 

 species was found half way down the burrow, and another 

 at the very bottom. No prey nor pocket was found; 

 hence we concluded that the burrow was evidently in 

 course of construction. Likewise it seemed improbable 



