384 WILLIAM MORTON WHEELER 



on the other. The question then presents itself : Do Ph. apivorus 

 and A. frigidus represent an advance on Cerceris or are the'con- 

 ditions in this genus derived from those of Ph. apivorus ? In 

 other words, is the Bembecine a primitive or a secondary method 

 of caring for the young among the solitary wasps? Undoubt- 

 edly most observers would be inclined to regard Bembex as 

 representing a later phylogenetic stage and one leading to the 

 conditions in the social w T asps, but the Peckhams take a different 

 view. "It may be possible, then," they say, "that all wasps 

 originally fed their larvae from day to day as Bembex now does, 

 and that while the instinct of paralyzing the prey and of storing 

 the whole supply of food once for all was working itself out 

 among the solitary wasps, the instincts connected with life in 

 a true society, and of joining together in the work of feeding 

 the larvae, have, on the other hand, developed into those of 

 our wasp communities." 



It is difficult to decide between the evolutionary alternatives 

 here indicated, but analogy with the phylogenetic history of the 

 bees, in which two precisely similar methods of rearing the 

 young occur, certainly points to the Bembecine method as 

 secondary. This view is also sustained by the sporadic and 

 independent occurrence in several highly specialized groups of 

 wasps of this method as the one best adapted to certain pecu- 

 liar conditions. Such cases are Aphilanthops frigidus and Phil- 

 antus apivorus. Two others are cited by the Peckhams, one in 

 the genus Sphex (Ammophila), where they found "an instance 

 which looks like a connecting link between the habits of Bembex 

 and those of the solitary species. A. urnaria stores one cater- 

 pillar, lays an egg on it, catches another and stores it as soon 

 as she can and then closes the nest. As a usual thing, no doubt, 

 the nest is finally closed before the egg is hatched, so that she 

 never sees her larva. In one of our instances, however, the 

 capture of the second caterpillar was so much delayed that 

 when it was brought in the mother wasp found a larva of a day 

 old feasting on the one already provided." The other case is 

 that of Lyroda subita Say, which these authors found to re- 

 semble Bembex in feeding its larva from day to day on small 

 crickets. Most instructive in this connection, however, is the 

 Aphilanthops, because its method of collecting a supply of queen 

 ants before feeding them one by one to the growing larva, indi- 



