82 
Some Solitary Wasps of Texas. 
beside the entrance, backs down and drags it into the nest. Rho- 
palum ( Crabro ) abdominaie and Thyreopm (Crabro) argus 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 this 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. Monedula Caro- 
lina leaves her nest open as often as she closes it, Bembex belfraegi 
and Bembidula close their nest more often than they leave it open. 
Miscophus and Hoplisoides always carefully close their nests be- 
fore leaving. Thyreopm , Alyson 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 Thomae, Alysonmelleus 
and Rhopalum abdominaie and Thryeopm argus, 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 , 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 texanrn and other 
fly-catchers hover around the droppings of cows and horses and 
around these animals themselves; Bembex belfraegi makes trees and 
bushes her hunting grounds; leaf-hopper catchers fly in and out 
among the grasses in search of food for their young; the cricket- 
killer Larra runs into and out of holes in the ground or under 
stones ; Microbembex glides gracefully through the woods satisfied 
with the first insect or part of an insect that comes to view. 
