400 



Insect Architecture. 



the same in several instances. In some of these insects the 

 ovipositor is conspicuously long, even when the insect is at 

 rest ; but in others, not above a line or two of it is visible, 

 till the belly of the insect be gently pressed. When this is 

 done to the fly that produces the currant-gall of the oak, 

 the ovipositor may be seen issuing from a sheath in form of 

 a small curved needle, of a chestnut-brown colour, and of 

 a horny substance, and three times as long as it at first 

 appeared. 



What is most remarkable in this ovipositor is, that it is 

 much longer than the whole body of the insect, in whose 

 belly it is lodged in a sheath, and, from its horny nature, it 



Gall-fly, arid mechanism of ovipositor, great'y magnified. 



cannot be either shortened or lengthened. It is on this 

 account that it is bent into the same curve as the body of 

 the insect. The mechanism by which this is effected is 

 similar to that of the tongue of the woodpeckers (Picidce), 

 which, though rather short, can be darted out far beyond 

 the beak, by means of a forked bone at the root of the 

 tongue, which is thin and rolled up like the spring of a 

 watch. The base of the ovipositor of the gall-fly -is, in a 

 similar way, placed near the anus, runs along the curvature 

 of the back, makes a turn at the breast, and then, following 



