Some Solitary Wasps of Texas. 43 



(e) Rhopolum (Crabro) Abdominale (Fox). 



This wasp is rather abundant in August and September. The 

 sexes can be readily distinguished as they fly around the low vege- 

 tation of the woods. The males have but one color, being wholly 

 black, while the abdomen of the females is bright red in color. 

 The thorax is very broad, which makes the abdomen, tapering grad- 

 ually toward the pedicle as in the case of Trypoxylon, look very 

 narrow. R. abdominale reminds me of Trypoxylon more than any 

 other wasp in the manner of its flight, for both, while out hunting, 

 are almost constantly on the wing and have a way of displaying 

 their curiosity by touching with their antennae every leaf or stick 

 or blade of grass in their path. 



Like Diodontus americanus, so well described by the Peckhams, 

 abdominale has the habit of flying into her open door-way. It was 

 this which first called my attention to her on September 14. The 

 entrance to the wasp's nest was a tiny hole in the middle of a small 

 flat elevation in the sand. The wasp approached the nest from 

 various sides, but whatever direction she came from, she first took 

 up a position directly opposite the entrance to her nest, where she 

 hovered for the twinkling of an eye, — just long enough to give me 

 a glimpse of the green leaf-hopper, which protruded a little beyond 

 her red abdomen. After this momentary quiver in front of the 

 nest, abdominale takes a beautiful bee-line right into her open por- 

 tal. It is a pretty sight to see this dive into the nest; it seems to 

 indicate a wonderfully keen sight for an insect thus to see the 

 tiny hole from the height of four or five inches and to judge her 

 flight so truly. 



is!, abdominale captures the same prey as Alyson melleus, leaf- 

 hoppers of the species Tettigonia bifida. Say. She is a wasp of 

 half the length of her competitor, but it takes her less time to catch 

 her prey. On September 14th, she brought home seventeen to 

 twenty leaf-hoppers, thirteen of which I saw carried in. The times 

 at which this was done are as follows : 10 :40, 10 :55, 11 :05, 11 :20, 

 11:37, 11:35, 11:53, 11:57, 1:50, 1:57, 3:05, 2:09, 3:37. On 

 each trip she remained inside but a few seconds. Her white sil- 

 very face was the first to appear at the entrance. Here she waited 

 but an instant before she was off like a flash, often so quickly that 

 I did not notice the direction of her flight. 



Thyreopus (Crabro) argus shows the same haste in getting away 

 from her nest and displays great acrobatic powers in the grace with 



