NO. 6 GRASSHOPPER ABDOMEN SNODGRASS 55 



The excavation of the egg cavity in the ground and the deposition 

 of the eggs therein have frequently been described in a general way, 

 but the process has been closely studied in the case of Anacridiuni 

 aegyptium by Fedorov (1927), who confined females of this species 

 in cages each having a narrow, glass-walled extension of the floor, 

 7 mm wide, filled with earth. The diameter of the female's abdomen 

 being 7 mm, the procedure of digging and oviposition could be ob- 

 served and photographed. 



The female grasshopper, according to Fedorov's account, at the be- 

 ginning of excavation arches her abdomen upward and directs the tip 

 of the ovipositor downward against the soil. The valves of the ovi- 

 positor now begin opening and closing, making a hole in the earth, 

 and the ovipositor gradually enters deeper and deeper, while the ab- 

 domen extends. The lengthening of the abdomen is accompanied by 

 an unfolding of the conjunctival membranes principally between seg- 

 ments IV and V, V and VI, and VI and VII, and to a lesser degree 

 of those between segments /// and IV, and VII and VIII. The seg- 

 ments beyond the eighth do not extend, but are even more closely 

 drawn together than usual. The entire extended abdomen may reach 

 a length of 9 or 10 cm, its ordinary length being about 3^ cm. While 

 digging, the part of the abdomen beyond the sixth segment twists 

 through an angle of 90°, now to one side, now to the other. The 

 entire process of excavating the cavity in suitable earth without special 

 obstacles takes from i to i^ hours. " The whole complex work of 

 digging," Fedorov says, " may be analyzed as consisting of the follow- 

 ing simple movements : ( i ) putting the valves of the ovipositor to- 

 gether, (2) a jerk downward, and (3) opening the valves; apart 

 from that the ovipositor is turned by muscles now to the left, now to 

 the right." 



Most observers of ovipositing grasshoppers have been much puzzled 

 to understand the mechanism of the digging apparatus, or particularly 

 the means by which the abdomen is extended to such a great length 

 and apparently with sufficient force to penetrate the earth. Kiinckel 

 d'Herculais (1894) noted that the fully extended abdomen of Schisto- 

 cerca percgrina has a length of 8 cm, while the retracted abdomen, 

 though filled with eggs, is only 5 cm long. On dissecting specimens 

 with the abdomen protruded at maximum length he found the ali- 

 mentary canal to contain air ; by letting out the air the abdomen could 

 be restored to its ordinary size. Hence he concluded that the digging 

 insects swallow air into the alimentary tract in order to give the 

 abdomen the necessary extension, the surrounding blood serving to 

 regulate the pressure. Contrary to the opinion of most writers. 



