May, 1910.] 
Nesting Habits of Bembex. 
163 
NOTES ON THE NESTING HABITS OF BEMBEX 
NUBILIPENNIS. 
By J. B. Parker. 
While engaged in field work at Wilson, Kansas, in August, 
1909, I chanced upon the nesting site of a large solitary wasp 
that proved to be Bembex nubilipennis. The wasps of this 
species, known in that locality as “yellow jackets,” are hand- 
some insects, exceedingly fast on the wing and alert, nervous and 
cautious when about their nests. Though they are solitary 
wasps they nest in colonies and the nesting site under observation 
was in a driveway leading from the public road into a barnyard, 
where the earth in which the nests were placed was trampled so 
hard that much difficulty was experienced in opening them. The 
owner of the place stated that these wasps had nested there 
annually for a number of years and his statement was borne out 
by the number of old burrows discovered during the investigation. 
The burrows, penetrating to a depth of six or eight inches, 
enter the ground at an angle of about forty-five degrees; but 
there is no very great uniformity in this respect. At a distance 
of from eight to twelve inches from the entrance lateral branches 
are given off, which serve as brood chambers for the larvae. At 
the time of my observation no burrow was found with more than 
five of these chambers; most had four and a few had only three. 
In the chambers more than one larva may be reared, in which 
case the first is placed at the extreme end of the chamber and 
when full grown and encased a wall is placed across the chamber 
and another larva reared between this and the main part of the 
burrow. 
The wasp in digging uses the first pair of legs, turning the 
tarsi inward so as to make a pair of rakes out of the stout spines 
borne on the posterior sides of these segments. At that time the 
dust of the surface of the driveway lay about an inch deep and 
the horses in passing back and forth over the nests completely 
changed the appearance of the surface several times a day. But 
this did not seem to bother the wasps a great deal, for they 
almost invariably digged down through the dust directly to the 
mouth of a burrow. The burrow thus found, however, did not 
always prove to be the one desired ; in fact, one wasp was observed 
to dig into three different burrows before she found the one she 
sought. Whether the first two opened were hers also or the 
property of another wasp I had no means of finding out in the 
brief time at my command. On leaving the nest the wasp not 
only closes up the entrance but also carefully conceals all traces 
of it, so carefully, indeed, that she has quite as much trouble at 
times in finding the entrance as she does when the horses have 
