48 THE AMERICAN MONTHLY [Feb. 



son. In fact I think tliey take very little, if any, food after 

 reaching the winged state. 



The ovipositor is an instrument used by the female for 

 making incisions in the twigs of trees in which to deposit 

 her eggs. It is about three-tenths of an inch in length 

 and is attached to the hinder extremity of the under side 

 of the abdomen, and protected by lying in a longitudinal 

 groove into which it fits like a surgical instrument in its 

 case. It consists of three parts ; two blades, furnished 

 with saws at their extremity, where they are consider- 

 ably enlarged and a central piece, called by some a sheath, 

 but which is nearly enclosed by the two exterior saw- 

 blades. The extremity of all three is shown in figure 3, 

 which represents them as seen from the under, (outer) 

 side, each saw blade carries on its inner side a tube, 

 (oviduct), which opens on the inner side near the extrem- 

 ity of the saw (0,0, figure 3) by a kind of flap through 

 which the eggs are extruded. These saws are a micros- 

 copical study, for while figure 3 fairly represents the ap- 

 pearance on the under side, in which view the saw-teeth 

 are seen to consist inwardly of a row of hooks pointing in a 

 direction opposite the extremity, and laterally of rounded 

 teeth with extremely sharp edges directed backward, or 

 toward the end of the saw. If examined from the oppo- 

 site side, the teeth resemble those of a file, arranged 

 obliquely and spirally from a line along the center out- 

 ward over the sides. When one of the ovipositors is 

 detached, and a lateral view is taken, the same spiral ar- 

 rangement of teeth is seen, with a set of sharp hooks on 

 the outer side pointing in an opposite direction to the 

 knife-edged teeth seen an figure 3. 



In cutting a channel for her eggs the insect closes her 

 legs around the twig and forcing the ovipositor saws be- 

 neath the bark and into the soft sap wood, works them 

 backwards and forwards, cutting loose but not removing 



