Some Solitary Wasps of Texas, 25 



from two to twelve mm. in length. Some of the bugs were per- 

 fectly dry, others were fresh when brought into the nest. 



(7) Small tree-hoppers, Tettigonia bifida. Say. the species 

 which form the sole prey of Ally son mellens and of Rhopalum ah- 

 dominale. 



(8) Polistes rubiginosus, so dry that it broke apart while Micro- 

 hemhex was carrying it. 



(9) Fresh grass-hopper, which I killed and threw on the nest- 

 ing-ground, was picked up by a Microhenihex, as was also a dry 

 Syrpliid. 



(10) Dry yellow Mutillid. 



(11) Old Orthopterous pupa-case with dry dead pupa inside. 

 Of all the things which Microhenihex feeds to her larvae, these last 

 two things are the toughest. The Mutillid must have been a most 

 indigestible morsel, for the skeleton is so tough that in the fresh 

 state it is very hard to drive a strong pin tlirough it. The Mutillid 

 was broken in two and the halves were carried off separately. 



The above account gives one a very fair idea of the diet of larval 

 Microhenihex. It thus seems probable that the larval food consists 

 mainly of insects, which the mother finds already dead and often 

 dry. This is, moreover, borne out by the manner of the wasp's hunt- 

 ing, in which she differs decidedly from the solitary wasps and re- 

 sembles markedly Polistes and Vespa. Bemhex hunts her flies in 

 a stormy fashion, flying around louder and faster than the prey 

 she captures. Microhenihex can be seen calmly flying through the 

 woods much like a dragon fly, steadily maintaining a level of a foot 

 from the ground. That she also attacks live insects is shown in 

 that she attacks ants and in that her caterpillars are always limp 

 and fresh. A fresh juicy caterpillar sandwiched in between a lot of 

 old dry insects must indeed be a very welcome morsel for the grow- 

 ing larva. 



It would thus seem that Microhenihex, contenting herself with any 

 insect she finds, has an advantage over Bembex, her nearest relative, 

 and Monedula, both of which feed their larvae from day to day. But 

 quantity alone does not bring the advantage. No doubt Bemhex, 

 knowing the habits of her prey, and having developed a skill in its 

 capture (being a specialist in the art of fly-catching) , can collect as 

 much real nutritive substance as Microhemhex. Though more gen- 

 eralized in the manner of procuring food, Microhemhex has devel- 

 oped an improvement in her condition over Bemhex tex. in that she 



