170 CYXIPID.E, OR GALL-FLIES. 



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,"- 

 which are found on the borders of the Dead Sea, and which 

 have been said " to appear outwardly tempting to the eye, but to 

 turn to ashes on the lips," are nothing else than galls of a softer 

 consistence, produced from the same Oak by the attacks of an- 

 other species of Cynips. The " oak-apples " of our own country 

 are large galls found upon the young shoots of the Oak ; the 

 leaves sometimes produce, besides larger galls, a multitude of 

 little spangled discs, of a reddish colour, which contain the 

 Iarva3 of a small species of Cynips ; the parts of fructification are 

 sometimes attacked by a species, the galls of which hang on the 

 catkins like a bunch of currants ; and the root produces a large 

 woody gall, inhabited by a species of Cynips, of which 1100 

 individuals have been found in a single gall. The Oak is by no 

 means the only species of vegetable infected by these insects ; 

 but a larger number of Gall-flies appear to be restricted to it 

 than to any other plant. The Rose is subject to the attacks of 

 one species, which causes the flower-bud to be developed into a 

 gall in a very curious manner. An insect, considered as belong- 



