182 TRANSFORMATIONS OF INSECTS. 
The large engraving shows the galls of the insect. They are 
cellular, and are aggregated in masses upon the twigs. 
A very common species of Cynips—Cynips aptera—produces 
great galls upon the roots of the oak, and it is a most remarkable 
thing that neither the males nor the females should have wings. 
The gall nuts of commerce, which are used as dyes, and to 
make ink and tinctures, and whence gallic acid is derived, are 
produced by the punctures of Cynips galle tinctoriga. These 
insects affect an Eastern species of oak, Quercus infectoria, and 
their galls are remarkably hard, round, and tuberculated. They 
Female. 
Cynips terminalis. 
only contain one larva. The cellule is moderately capacious, but 
the walls are very thick; nevertheless, the little Cyzzps perforates 
them without much difficulty, in order to come to the light of 
day. 
The rose fungus is one of the most curious galls; it is pro- 
duced by a Cyzips, and is found upon the hedge roses and sweet- 
briars. The adult insect which produces these excrescences is 
about the fifth of an inch long. Its transparent wings are 
slightly clouded, and it is of a glossy black colour. The females 
lay their eggs towards the end of May or the beginning of June, 
and the galls soon form, but they grow at first very slowly, and 
subsequently quickly, so that they attain their full size on the 
approach of cold weather. Sometimes the galls are round, or 
flat, at others they are irregular in shape, and resemble medlars, 
and they are about the same size as those fruits. They are 
