316 INSECTS AT HOME. 



otihers, of which the common ' oak-apple ' gall and the ' bede- 

 guar' of the rose are familiar examples, a number of cells are 

 enclosed in a common gall, and each insect inhabits its own 

 cell. 



We will now examine in detail a few of the most prominent 

 insects of this group. The insect on Plate IX., to which refer- 

 ence has just been made, belongs to the typical genus of the 

 family. By some entomologists it is called Cynips Kollari^ in 

 honour of the well-known entomologist, and by some it is en- 

 titled Cynips ligiticola, in consequence of the hard and almost 

 woody structure of the gall. In this genus the abdomen is 

 rather egg-shaped, and there is a small, but boldly marked 

 triangular submarginal cell. The antennas of the male have 

 fifteen, and the female fourteen joints. The colour of this 

 species is dull plain brown. 



The rapid manner in which insects can spread themselves 

 over a district when the conditions are favourable is well ex- 

 empliiied by this Gall-fly. Comparatively a few years ago it 

 was unknown in the vicinity of London. But Mr. F. Smith 

 brought from Devonshire a branch on which were a number of 

 the galls, and fastened it m an oak hedge. Next year the oaks 

 bore these galls in numbers, and the insect has so rapidly made 

 its way that its galls are now better known thnn those of any 

 other species. They are so plentiful that they are even strung 

 on wires, and made into ornamental baskets for holding ferns. 

 I have in my garden an oak hedge which is thickly studded 

 with the round, hard galls. Even in summer-time, when the 

 leaves are on the trees, these galls are easily seen ; but in the 

 winter, when no foliage obstructs the sight, they are the most 

 conspicuoTis objects in the hedge. In this part of the country, 

 i e. West Kent, there is great abundance of oak underwood, and 

 in consequence this species, in common with other oak-lovmg 

 insects, finds ample siibsistence. 



I have had great numbers of these Gall-flies, and when the 

 first batch escaped from the galls, I was sadly disappointed at 

 the dull, sombre brown colour, and altogether commonplace 

 look of the insect. Still, owing to the size of the Cynips, the 

 structure of the ovipositor can be easily made out with the 

 aid of a tolerable microscope and a fair stock of patience. 



