42 
Some Solitary Wasps of Texas. 
the colonies. This recalls by way of contrast the fierce combat of 
two Ammofihilae which happened to dig their nests near each other. 
Bembex is furthermore said to show a social trait in the co-operation 
of the individuals in driving away parasitic flies. This is, however, 
more imaginary than real, for the fly is not killed nor is it driven 
away from the colony but merely from one individual’s nest to an- 
other’s. 
Both Bembex and Microbembex are common species throughout 
the sandy woods. Every path or road or other area devoid of vege- 
tation is occupied by individuals of these flourishing species. If an 
open spot is a favorable nesting place, wasps may congregate there 
in numbers sufficient to riddle the surface with holes, thus forming 
an extensive colony. Now, since such spots are not common, the 
thought suggested itself that the very numbers of the wasps forced 
them to occupy the same patch of ground, to dig their nests side by 
side, and thus by virtue of their familiarity with one another to 
live together in comparative peace. The tolerance of one another’s 
presence would then be the first trace of the social instinct. The 
fact that the two different genera live together as peacefully as does 
Bembex with Microbembex seems to point to the* same conclusion. 
Moreover, neither genus seems to show a marked predilection for 
living in the colony, for isolated individuals of both will be found 
throughout the woods, evidently as happy as when joining in the 
busy hum of a colony in the noon-day sun. 
May it not even be that in this way numbers was the first stimulus 
toward social life as shown *by a trace of it in Bembex and Microbem- 
bex ? 
