Some Solitary Vii'asps of Texas. 69 



and on entering it, head foremost, deftly pass their prey back from 

 the middle to the hind pair of legs. Microbembex, for example, 

 never fails to do this regardless of the size, weight, or shape of the 

 prey. Ammophila, like Pnonomjx Tliomae, lays her victim down 

 beside the entrance, backs down and drags it into the nest. Rho- 

 palum (Crabro) abdominals and Thyreopiis (Crabro) argiis display 

 great skill and precision in slipping into their nest, the former 

 actually diving into her open door-way without stopping at the en- 

 trance. 



The manner of entering the nest depends somewhat on whether 

 the nest is open or closed when the wasp arrives. In tliis particular 

 there is great variation in the species as well as in the individuals. 

 Microbembex usually closes her nest on leaving it but sometimes 

 leaves it open; with Bembex texanus the exact opposite habit 

 prevails. Ammophila Procera closes her nest after each visit in 

 cases where she stores more than one caterpillar. Manedula Caro- 

 lina leaves her nest open as often as she closes it, Bembex belfraegi 

 and Beinhidula close their nest more often than they leave it open. 

 Miscophus and TlopUsoides always carefully close their nests be- 

 fore leaving. Thyreopiis, Ahjson and all solitary wasps that use 

 mud in their architecture never close their nests on leaving on a 

 hunting expedition; the female Trypoxylon, however, leaves the 

 male on guard in her absence. Among the spider-ravishers that 

 capture their prey before digging their nests many carry their spi- 

 der out of reach of predatory enemies until the nest is ready 

 (Fig. 5). 



A given species of wasp will usually confine herself to a particular 

 kind of prey : a bug-catcher will always take bugs, a spider-ravisher 

 never anything but spiders, an Ammophila only caterpillars, etc. 

 Sometimes, as in the case of Priononyx Thoniae, Alysonmelleus 

 and Rhopalum abdominale and Tliryeopus argns, the specialization 

 is so complete that a certain species of grasshopper, leaf-hopper 

 or fly is adhered to, all other grasshoppers, leafhoppers or flies being 

 refused. The opposite habit, a universality of insect-food, obtains 

 with Microbembex J which carries to her young any insect dead or 

 alive or any part of an insect which she can find and capture 

 (Chap. III.) 



Each species of wasp has learned the life habits of its prey and 

 therefore frequents the latter's haunts. Bembex texaniu^ and other 

 fly-catchers hover around the droppings of cows and horses and 



