338 INSECT ARCHITECTURE. 



cherries. The galls resemble currants whicli have fallen 

 from the tree before being ripe. These galls do not se^m 

 to differ from those formed on the leaves of the oak ; and 

 are probably the production of the same insect, which 

 selects the catkin in preference, by the same instinct that 

 the oak-apple gall-fly, as we have seen, sometimes deposits 

 its eggs in the bark of the oak near the root. 



The gall of the oak, which forms an important dye-stnff, 

 and is used in making writing-ink, is also produced by a 

 Cynips, and has been described in the ' Library of Entertain- 

 ing Knowledge' (Vegetable Substances, p. 10). The employ- 

 ment of the Cynips psenes for ripening figs is described in 

 the same volume, p. 244. 



Gall of a Hawthorn Weevil. 



In May 1829, we found on a hawthorn at Lee, in Kent, 

 the leaves at the extremity of a branch neatly folded up in 

 a bundle, but not quite so closely as is usual in the case of 

 leaf-rolling caterpillars. On opening them, there was no 

 caterpillar to be seen, the centre being occupied with a 

 roundish, brown -coloured, woody substance, similar to some 

 excrescences made by gall-insects (^Cynips). Had we been 

 aware of its real nature, we should have put it immediately 

 under a glass or in a box, till the contained insect had deve- 

 loped itself; but instead of this, we opened the ball, where 

 we found a small yellowish grub coiled up, and feeding on 

 the exuding juices- of the tree. As we could not replace the 

 grub in its cell, part of the walls of which we had unfortu- 

 nately broken, we put it in a small pasteboard box with a 

 fresh shoot of hawthorn, expecting that it might construct 

 a fresh cell. This, however, it was probably incompetent 

 to perform : it did not at least make the attempt, and 

 neither did it seem to feed on the fresh branch, keeping in 

 preference to the ruins of its former cell. To our great 

 surprise, although it was thus exposed to the air, and 

 deprived of a considerable portion of its nourishment, both 

 from the part of the cell having been broken off, and from 

 the juices of the branch having been dried up, the insect 



