no. 2173. A REVISION OF THE BEMBICINE WASPS— PARKER. 14 1 



discovered before its situation had been disturbed and its relation to 

 the burrow could be positively determined the cell was found in the 

 tunnel of the burrow from one to three inches from the remains of the 

 food left in the brood chamber. Whether the cells found in the sand 

 at one side of the brood chamber (a circumstance that was observed 

 several times) was formed there by the larva, or had been dislodged in 

 the digging or was formed in another tunnel not associated with the 

 brood chamber near it, are questions that I failed to settle to my own 

 satisfaction. The fact that some of the larvae in my breeding vials 

 burrowed for an inch or more into the sand shows that the larva can 

 if it chooses make its way into the sand from the brood chamber with- 

 out the aid of a tunnel. 



After encasing the insect remains in the larval form until the fol- 

 lowing spring. Just when the change to the pupa state is made — that 

 is, how long the pupa stage lasts — I have not determined, since all the 

 cocoons secured from the sands after I took up my work on June 17, 

 contained either the pupae of the wasp or larvae or pupae of para- 

 sites. When the wasp is ready to emerge it cuts off a circular cap 

 from the end of the cell and comes out. All cocoons from which the 

 wasp had emerged were found densely filled with sand, evidently dig- 

 ged back into them by the wasps at the time of emergence. 



No very careful attempt to determine the parasites that prey upon 

 M. momodonta was made. The most common one is a species of 

 Bombylid fly, Exoprosopa fascipennis Say, which was repeatedly 

 taken in the act of ovipositing in the sand at the entrance to the 

 burrows of the wasp and a pupa of which was taken from a cocoon 

 of this species. Another parasite taken from a cocoon is a species of 

 MutiUid wasp, Dasymubilla, species ? In additon to these a num- 

 ber of small parasitic flies, probably Tachinids, were always busy 

 about the entrance to the burrows awaiting an opportunity to dash 

 into the opening behind the wasp as she entered her nest and de- 

 posited an egg upon the food she carried in for her young. The 

 little red ants that interfered with my breeding operations also tun- 

 nel through the sand and destroy the contents of every nest that 

 they chance to find. 



EXPLANATION OF FIGURES. 



Figures 1 to 6, inclusive, were made from microscopic projections of balsam mounts 

 of the wings. They are, therefore, exact in outline and proportions and since all 

 were drawn on the same scale of magnification the relative sizes are shown. No other 

 drawings were made from balsam mounts; they were made directly from the naked 

 objects. In preparing the genital stipites the wasps were relaxed and the genitalia 

 exserted and allowed to dry either attached to the abdomen of the wasp or more fre- 

 quently detached and mounted on strips of paper placed on the pin. All figures 

 except those of the wings are camera lucida drawings made with a Bausch & Lomb 

 microscope, using a 48 mm. objective and 10X ocular, except in the case of figure 80, 

 where a 16 mm. objective and 5X ocular were used, and in the case of figures 218 to 

 230, inclusive, where a 48 mm. objective and 15X ocular were employed. Wherever 



