no. 2173. A REVISION OF THE BEMBICINE WASPS— PARKER. 129 



thereafter so as to permit the larva to reach the internal organs it 

 fed freely and after a day or two it had no difficulty in feeding upon 

 flies that were given intact. 



The larva feeds voraciously, grows rapidly, and the mother wasp 

 is kept busy bringing in food for her hungry offspring. In my breed- 

 ing experiments the shortest period within which the larva passed 

 from hatching to the formation of its cocoon — that is, the time during 

 which feeding occurred — was four days. From my observations in 

 the field I am inclined to think that the time of feeding in the larval 

 stage, provided weather conditions do not prevent the mother from 

 keeping on hand a plentiful supply of food, is on the average about 

 six or seven days. Although I can not state the exact number of 

 flies consumed by any one larva of this species, I should estimate the 

 number of house-flies required to mature the larva to be at least 50. 

 In my breeding experiments I made a practice of supplying more 

 flies than the larva could consume in a day and then on each momma- 

 supplying fresh flies after removing from the cell all partly eaten and 

 untouched flies therein. Consequently the exact number was not 

 determined. 



The wasp carries her prey ventral side up beneath her body tightly 

 clasped with her middle legs. She retains her hold upon her prey 

 while opening the nest, resting on the posterior pair of feet while she 

 digs open the entrance with her front pair. Wessenberg-Lund states 

 that rostrata lays her fly aside while opening the nest, pausing in her 

 work from time to time to make sure the fly is safe. I never saw 

 spinolae lay aside her fly when opening her nest save in cases when 

 the sand had been disturbed so as to make it difficult for her to find 

 the entrance to the nest. In such cases the fly was discarded entirely 

 and left lying on the sand. The Peckhams say of spinolae that ' ' some- 

 times she drops the fly behind her and then, turning around, pulls it 

 in with her mandibles." In my observations I have never seen spi- 

 nolae take a fly into the nest in any way other than the usual fashion. 

 Melander in his article on Bembix (see bibliography) makes the fol- 

 lowing statements: 



When the nest is of the requisite depth the wasp carefully covers it with loosened 

 soil, concealing the opening. She then departs to sting a fly whereon to deposit her 

 egg. The fly is carried to the nest and left at the door while the wasp digs through. 

 She then descends to the bottom of the nest and returning to the doorway for the fly 

 brings it down as food for her young one. 



It is not possible to say with certainty to which species of Bembix 

 these statements refer, but the fact that one of the illustrations in 

 the article is labeled/' Adult of Bembex spinolae, enlarged five times," 

 would seem to show that the article was written with this species in 

 mind. Since two other species quite similar to spinolae are known 

 to occur in northwestern United States, primauestate and comata, it 

 65008°— Proc.N.M.vol.52— 17 9 



