10 BULLETIN 293, U. S. DEPARTMENT OF AGRICULTURE. 



Crouching close to the ground, it will raise the posterior pair of legs 

 above the abdomen in the shape of an inverted V, whereupon it will 

 remain perfectly quiet until the wasp has apparently departed. 

 Though the Priononyx will occasionally attack a nymph while in this 

 protective attitude, a severe struggle generally ensues, with the grass- 

 hopper infrequently the victor. 



A large number of the nymphs which have been stung by Prio- 

 nonyx and left upon the prairie while she is building the nest are in 

 the meantime larviposited upon by Sarcophaga kellyi. 



The nest is usually built in compact sand. Between railroad tracks 

 and along the right of ways are also desirable nesting places. The 

 excavation of the burrow is commenced by the female rapidly 

 scratching away the surface with the anterior pair of legs. As the 

 depth of the burrow increases the head is cooperatively brought into 

 play with the workings of the anterior legs, when finally the exca- 

 vation of the burrow is completed by the wasp bringing huge 

 mouthfuls of the soil to the surface. The burrow is excavated almost 

 vertically downward to a depth of 1J to 2 inches and about one- 

 half inch in diameter. The bottom of the burrow is then excavated 

 in a horizontal direction until a cavity is made sufficiently large con- 

 veniently to permit of a nymph being placed within it. In drag- 

 ging the nymph to the burrow the wasp assumes a horizontal posi- 

 tion astraddle the victim. Seizing the nymph with her mandibles 

 at the base of the antennae, she drags it venter down to the entrance 

 of the burrow. Then facing the nymph, still holding it at the base 

 of the antennae, she backs into the burrow, dragging in the nymph 

 head foremost behind her. Placing the nymph in the horizontal 

 cavity at the base of the burrow, venter down, in a horizontal posi- 

 tion, she deposits a single egg. This egg, white in color, elongate 

 oval, and somewhat curved, is invariably attached to the tender 

 membrane at the base of the posterior coxa. 



The egg having been deposited, the wasp proceeds to the surface. 

 Taking a position, back to the burrow, she rapidly scratches the 

 excavated soil into the hole. From time to time she packs down the 

 soil with her head, which she uses as a most efficient ramming instru- 

 ment. The excavation filled, the wasp carries small sticks, stones, 

 cinders, and the like — these often much heavier than the wasp her- 

 self — and places them over the burrow. The time elapsing from the 

 moment the nest is started until its completion usually varies from 

 30 minutes to 1 hour. 



Though it is virtually impossible for the human eye to locate a 

 completed Priononyx nest, there is a bembecid wasp, Megastizus 

 unicinctus Say, a secondary upon Pivononyrc atrata, which without 

 the least difficulty locates the Priononyx nest with the greatest exacti- 



