162 



SIRICIDJE. CYNIPID^, OR GALL-FLIES. 



largest species are inhabitants. When full grown, they form 

 a slender silken cocoon, mixed with chips of wood, at the 



extremity of the 

 burrow ; and here 

 they undergo their 

 final transformation . 

 The perfect Insects 

 are among the largest 

 of the order; they 

 are remarkable for 

 the very cylindrical 

 form of their bodies, 

 and for the hum- 

 ming sound which 

 they make when on 



FIG. 384. SIREX GIGANTEUS. j.] ie w i n g 



689. SECTION II. In the section of ACULEATA ENTOMO- 

 PHAGA, the first family, that of CYNIPID^E, or Gall-flies, rather 

 corresponds with the preceding in its general habits, and in the 

 diet of the larvae. These insects puncture, with their ovipositor, 

 the surface of the leaves, buds, stalks, and young stems and roots, 

 of various plants and trees ; and they increase the aperture by 

 means of the toothed edge, forming a kind of saw, with which 

 the extremity of this organ is armed. In this aperture they 

 deposit, besides the egg, a drop of fluid, which seems to be 

 peculiarly irritating in its character ; causing the production of 

 tumours or galls., of various sizes, shapes, and colours ; the solid 

 interior of which becomes the food of the larva when hatched. 

 It is a remarkable circumstance, that the very same tree should 

 produce, on its different parts, galls of very different forms and 

 of various degrees of consistency, according to the species of 

 Cynips by which it has been punctured. The hardest is the 

 common Gall-nut, which is employed in the manufacture of ink, 

 and also, to a far greater extent, in the process of dyeing black 

 (VEGET. PHYSIOL. 399). This is produced in the Levant, 

 upon a low-growing species of Oak, the Quercus infectoria. It 

 has been recently ascertained, that the " apples of Sodom,"- 



