Some Solitary Wasps of Texas. 23: 



turns, to search for her prey, she docs so by flying slowly round and 

 round in the vicinity of the caterpillar. 



■ These tactics expose the prey to considerable danger from para- 

 sitic flies. Indeed, I once noticed two grey Muscids with reddish 

 abdomens follow a wasp with her caterpillar for a great distance. _ 

 Their persistence greatly agitated Microhemhex^ and she several 

 times left the caterpillar and pounced upon one or the other fly 

 and threw it to the ground. The blow was, however^ not serious, 

 for the fly continued without fear as before. Why the wasp did 

 not kill the interlopers on the spot, I can not understand. Fabre, as 

 well as the Peckhams, wonder at the laxness of Bemhex in her treat- 

 ment of parasitic flies which she keeps driving away instead of 

 killing them once for all. This would be easy for her to do, if she 

 were so inclined; a single sting, applied as it is to another fly that 

 is to serve as food, would forever rid her of one of these trouble- 

 some intruders. Both the French and the American observers fail 

 to offer an explanation for the phenomenon. It may be that the 

 sting is not used on other occasions than the capture of prey, just 

 as is the case of the queen domestic bee the sting is never drawn 

 except in mortal combat with a rival queen. Since it is always 

 certain species of parasitic flies that are in attendance upon the 

 wasps, it may be through mere familiarity with the flies, and the 

 presence of those so near to the nest, that they are so much tolerated. 

 For the flies are in every way treated like other wasps of the same 

 species. I have seen a Bembex knock down another Bemhex or a 

 Ilicrohembex and have even seen them clinch as if earnestly en- 

 gaged in fighting, but they never drew their stings. 



Notwithstanding the half hearted efforts of Microhemhex to rid 

 herself of her enemies, these follow her to her nest. Having ar-, 

 rived at the nest the wasp opens it, grasps the caterpillar with her 

 hind legs and drags it inside, walking in head foremost. Ammo- 

 phila, it will be remembered, backs into the nest and pulls her cater- 

 pillar in backwards. 



(2) Another common object brought in by Microhemhex, was 

 the leg of a grasshopper. On several occasions I saw this carried 

 along in the same way that the caterpillar was carried. Once an 

 ant was making away with the leg of a grasshopper which it had 

 probably purloined from the Microhemhex herself. The wasp many 

 times picked up the leg but the ant would not let go, but forced 

 the wasp to drop it, until the latter gave up the fight. 



