THE GALL INSECT, 147 



because they are of no use in dyeing. One of 

 these is represented in the frontispiece to this 

 chapter, and is remarkable for its large size. It 

 is spongy, very light, of a reddish brown colour, 

 and covered with a resinous matter. It is also 

 furnished with a circular range of tubercles, placed 

 near its greatest circumference. This is produced 

 by a different insect, called by Olivier Diplolepis 

 gallce resinosce ; a figure of which is also given on 

 the right hand side. 



Gall-flies of various kinds attack our oak trees 

 in this country, and also our willows, hawthorns, 

 roses, &c. A few words respecting the excres- 

 cences they produce, may therefore assist our ideas 

 of the proceedings of the valuable insect described 

 above. Very few persons are unacquainted with 

 oak-apples, or small roundish, flattened bodies 

 growing on the leaves of the oak. These are 

 sometimes tinged with brown, or pink, or pale 

 yellow, so as to appear not much unlike very small 

 apples, attached to the leaf. Each of these 

 curious bodies is formed by a small fly of the same 

 nature as that which forms the gall-nut. This 



