128 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



the nesting area to make excursions to the flowers in the vicinity in 

 order to feed on the nectar and presumably also upon the pollen. 

 The males also dig burrows in the sand, in which they spend the nights 

 and the days too during unfavorable weather. These burrows are 

 short and extend to the depth of only an inch or two below the sur- 

 face. It is an interesting sight on a hot summer day when a sudden 

 shower comes up to see these males hasten to the nesting area and 

 bury themselves in the sand. 



There has been much speculation as to whether Bemhix rears more 

 than one larva at a time and opinions on this point differ. So far as 

 I am aware no positive evidence bearing on this matter has been pre- 

 sented by other investigators and what I have obtained is not con- 

 clusive. In a preceding paper on the nesting habits of B. nubilipennis 

 Cresson, it was pointed out that this wasp forms a series of lateral 

 branches from the main tunnel and in these rears her larvae, but the 

 evidence obtained in that brief investigation tends to show that but 

 a single larva is reared at a time. My investigations of the nesting 

 habits of B. spinolae give evidence of the same character. On two 

 occasions, when keeping under observation a wasp that was busy car- 

 rying flies into her nest, she completed this task and sealed up the 

 nest. The sealing of the nest differs from the ordinary mode of closing 

 it, in that in the latter case only the entrance is closed, whereas in the 

 former the tunnel from the brood chamber to the opening is solidly 

 packed with sand. In each case noted the wasp after completing 

 her task of sealing up the nest searched about for a few minutes, and 

 without going out of my sight, began and completed a new nest within 

 which as soon as complete a fly was placed, upon which an egg was 

 deposited. 



No more flies are placed in the nest until the larva emerges from 

 the egg, which usually occurs at the expiration of one or two days 

 after its deposition. The young larva does not leave the egg, but 

 moves upward to the open end of the eggshell to which its posterior 

 end remains attached. From this vantage point it can reach with 

 its head to considerable distance on all sides. In no case observed 

 did the larval wasp devour the fly on which the egg was placed. To 

 do so would deprive the young larva of the advantage it enjoys in the 

 position it occupies — a position that appears to be essential to its 

 feeding upon the food provided by the mother wasp at this time. In 

 no case did I succeed in rearing in my breeding cells a larva that was 

 accidentally detached when small from the fly on which the egg was 

 placed. It is my conviction that the flies on which the young larva 

 first feeds are crushed or macerated for it by the mother wasp. In no 

 case did I find a newly-hatched larva in my breeding cells able to feed 

 upon house-flies that were given to it intact and a number of such 

 larvae died for me before I discovered this. By crushing the flies 



