﻿The Life History of Two Species of Nahidae 153 



OVIPOSITION 



Oviposition might be explained theoretically as follows : With 

 the bending-under of the abdomen the muscles locking the sheath 

 are relaxed, allowing its two sides to spring apart. At the same 

 time the ovipositors are let down and perhaps the initial piercing 

 done by the longer stylets. The innermost pair probably does most 

 of the rasping and drilling after the surface is ruptured, using 

 the second pair as a sleeve through which they are able to operate 

 up and down. The longer stylets also may aid in spreading the 

 opening during the passage of the egg and the withdrawal of the 

 innermost pair. The two spoon-shaped structures of the first pair 

 probably aid as e^g guides. 



Oviposition is an interesting phenomenon to watch. The first 

 part of the process seems to be that of testing the grass-stalk at 

 various places with the proboscis. If a nabid has oviposited at a 

 particular spot on a stem, she is quite sure to return to the same 

 vicinity a second or a third time. 



On June 17th a nabid was seen near the top of a grass-stalk 

 probing it with her proboscis. After a short time this w^as stopped 

 and the abdomen bent forward and under. The first two pairs of 

 legs were holding firmly to the opposite side of the grass-stalk. 

 Almost immediately the ovipositors were seen to swing downward 

 slowly. This motion was so slow and steady as to remind one of 

 the mechanical manipulation of a heavy piece of steel. The ends 

 of the stylets touched the grass-stalk near where the proboscis had 

 been. They were at first perpendicular to the stalk. There was 

 an apparent straining and a rhythmic jabbing motion of the 

 abdomen. The female seemed to exert every ounce of her effort 

 to pierce the outer grass wall. Sometimes with all the straining 

 she was unable to force her stylets in, then again after only a 

 short trial they would suddenly sink into the stem for their entire 

 length. They appeared to be guided somewhat by the female after 

 breaking through the hard exterior of the stalk. 



Several of these operations were timed. Once the ovipositor 

 w^as found to remain inserted for three minutes and ten seconds, 

 another time for three minutes and thirty-five seconds, and a third 

 time for only thirty seconds. On the withdraM-al of this egg- 

 apparatus nothing can be seen until after a few hours. The plant 

 tissues gradually shrink away from around the distal end of the 

 e^^ revealing the little egg-caps. 



There were cases in which nabids had oviposited through thin 

 blades of grass, the eggs extending entirely through and hanging 

 merely by means of the enlarged egg-caps. Some eggs were 

 inserted similarly, but with the distal end down. These eggs so 

 exposed to the air, did not seem to shrivel or lose their smooth 

 outline. 



The females were found to lay from fifteen to sixty-five eggs 

 each, and to have a laying period of about eighteen days. Since 

 these specimens may already have been laying before they were 

 captured, the figures in this respect are merely tentative. 



