INSECT ABDOMEN SNODGRASS 



63 



a small space on the .surface of the earth selected as the oviposition 

 site. The clearing operation is a strenuously performed task, the in- 

 sect hurriedly scratching away loose surface material with her fore 

 feet as if in desperate haste to prepare the spot, from which she may 

 remove in her jaws pellets and pebbles as large as her body. This 

 done, she reverses her position and jabs the ovipositor at the clear- 

 ing, or, at least, such is her evident intent, but often as not the aim 

 miscarries, quite unperceived by the impetuous cricket, and the subse- 

 quent insertion of the ovipositor is then made at a place entirely un- 

 touched in the work of preparation. 



At the beginning of oviposition the Gryllus female elevates herself 

 on her hind legs, thus raising the abdomen, and depresses the ovi- 

 positor until its shaft is directed posteriorly and downward at an angle 

 of about 45 degrees to the surface of the ground, as the tip is inserted 



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Fig. 20. — Sections of the shaft of the ovipositor of Gryllus assiiiiilis, showing 

 groove-and-ridge connections between the first and third valvulae. 



into the latter. Within the space of a minute, when working in soft 

 soil, the ovipositor is buried to full length, and the terminal part of 

 the abdomen comes in contact with the ground. During the insertion 

 process the two valvulae of each side glide rapidly back and forth a 

 short distance on each other, the corresponding blades of opposite 

 sides apparently working in unison. The egg enters the channel of the 

 ovipositor at the bases of the valvulae, passes along the entire length 

 of the shaft, and is extruded from the tip into the bottom of the ex- 

 cavation. During the withdrawal of the ovipositor, the organ is re- 

 peatedly thrust down into the cavity at successively shorter depths, 

 evidently to pack the soil above the egg. When the ovipositor is fully 

 extracted, the insect gives no further attention to the place where the 

 egg has been intrusted to the earth. These observations on Gryllus 

 were made on individuals in confinement. Ncmohius scratches over 

 the surface where the egg has been deposited before leaving it ; 

 Oecanthus plugs each egg cavity she makes in a twig with bark chew- 



