372 INSECT ARCHITECTURE. 



nl 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 cur- 

 rant-gall of the oak, the ovipositor may be seen issuing 

 from a sheath in form of a small curved needle, of a 

 chesnut-brown colour, and of a horny substance, and 

 three times as long as it at first appeared. 



Ovipositor of gall-fly, greatly magnified. 



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 cannot be either shortened or length- 

 ened. 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 simi- 

 lar way, placed near the anus, runs along the curva- 

 ture of the back, makes a turn at the breast, and 

 then, following the curve of the belly, appears again 

 near where it originates. We copy from Reaumur 

 his accurate sketch of this remarkable structure. 



