A WASP THAT PROVISIONS ITS NEST WITH QUEEN ANTS 381 



in nests containing old and empty cocoons and freshly stored 

 ants but no larvae, we may infer that after one larva has been 

 reared in the manner described above the mother sets about 

 providing for another in the same nest but in a fresh chamber. 

 Pupae nearly ready to hatch were found August 5 and freshly 

 pupated young August 16; young larvae were found on the 

 latter date and on August 8. The larva and cocoon closely re- 

 semble those of Cerceris rybiensis as figured by Marchal (1887). 

 If my interpretation of the feeding of the larva is correct, we 

 have in Aphilanthops a very interesting condition intermediate 

 between that of the great majority of solitary wasps, which 

 first collect pro\ T isions and then lay an egg upon them, and 

 that of Bembex, which lays its egg on a single fly and feeds the 

 hatching larva from day to day with fresh flies. If Fabre is 

 right in supposing that Bembex does not always give all the 

 captured prey to its young but keeps a portion of it tempo- 

 rarily out of the larva's reach in the burrow, we should have 

 an approach to Aphilanthops, which brings in its store before 

 beginning to feed its larva. This temporary storing of ants and 

 the fact that they are not killed outright as in Bembex, but merely 

 paralyzed, calls for an explanation. This, I believe, must be 

 sought in the peculiarity of the prey, which is quite unlike that 

 of other solitary wasps in that it can be obtained only at con- 

 siderable and irregular intervals of time, namely, during the 

 marriage flights of the various species of Formica. These flights 

 may, to be sure, occur any time between the middle of July and 

 the first of September, but nearly all the colonies in a given 

 locality celebrate their flight on the same date and often during 

 only a few hours, so that many days may elapse before there is 

 another flight. And although the wasps draw their supply of 

 prey from several different species of Formica, this does not 

 very greatly improve matters. In any event, the wasps have to 

 make hay while the sun shines and carry in as many ants as 

 they can secure before beginning to rear the larvae. The need 

 of thus temporarily storing the prey also explains why it is 

 paralyzed and not killed outright as in the case of Bembex, nor 

 mutilated before it is really fed to the young. Of course, it is 

 not impossible that the Bembecine method may also be em- 

 ployed bv Aphilanthops if nuptial flights of the ants occur in 

 quick succession so that there is no need to store the prey before 



