1934 ] 
Nesting Sites of Bembix nubilipennis 
243 
A NOTE ON THE ATTACHMENT OF THE WASP, 
BEMBIX NUBILIPPENNIS, TO THEIR 
NESTING SITES 
By Phil Rau 
Kirkwood, Mo. 
In “Wasp Studies Afield” in 1917 I describe the nesting 
behavior of Bembix nubilipennis. The wasps have emerged 
year after year in early summer, and then have dug their 
new tunnels in the same site where they were born, in this 
instance the hard-baked barren soil of a baseball diamond. 
This gave me at that time an opportunity to study four suc- 
cessive generations of these wasps in as many years. 
Dr. Wm. M. Wheeler in his introduction to the above work 
especially calls attention to the strong attachment of these 
wasps to their nesting site, for they keep to the same locality 
for generation after generation. “Such a habit,” says Dr. 
Wheeler, “has the ear-marks of great antiquity, and seems 
to indicate that the present type of nesting site is like the 
one in which the group originated.” This statement has 
caused me often to visit this site over a period of years, to 
see how long they would maintain this colony. The colony 
was first observed in a vacant lot in the heart of southwest 
St. Louis in 1914 ( loco citato pp. 1-36) and today, twenty 
years later, the colony is nesting in the same way in the 
same site. They have not spread to the surrounding grass 
plots or to a roadway nearby ; the population has not dimin- 
ished with the passing of the years, and neither has the pop- 
ulation increased during this period. There is one slight 
variation, however, in that a portion of the population has 
wandered away and become colonized in a second and 
smaller baseball diamond two hundred feet away. This 
smaller diamond was made ten years ago, and I watched it 
yearly to note any Bembix migration. I felt the site was 
suitable for Bembix, and it would be only a matter of time 
before they would become established. The new barren 
