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 "_vellow jackets," are hand- 

 some insects, exceedingly fast on the wing and alert, nervous and 

 cautious when about their nests. Though they are solitary 

 wasps thev 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 

 annualh- for a number of years and his statement was borne out 

 bv 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 

 alwavs 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 



