390 mSECT ARCHITECTURE. 



of the roots of cabbages, and the knob-hke galls on 

 turnips, called in some places the anhimj. They 

 are evidently beetles of an allied genus which form 

 the woody galls sometimes met with on the leaves of 

 the guelder-rose [Viburnum), the lime-tree [Tilia 

 europcta), and the beech (Fagus sijlvatica). 



There are also some two-winged flies which pro^ 

 duce woody galls on various plants, such as the 

 thistle-fly {Ttphriiis cardui, Latr.) The grubs of 

 this pretty fly produce on the leaf-stalks of thistles 

 an oblong woody knob. On the common white 

 briony {^Bnjonia clioica) of our hedges may be 

 found a very pretty fly of this genus, of a yellowish 

 brown colour, with pellucid wings, waved much 

 like those of the thistle-fly with a yellowish brown. 

 This fly lays its eggs near a joint of the stem, and 

 the grubs live upon its substance. The joint swells 

 out into an oval form, furrowed in several places, 

 and the fly is subsequently disclosed. In its perfect 

 state, it ieeds on the blossom of the briony.* Flies 

 of another minute family, the gall-gnats {Cccidomyice, 

 Latr.), pass the first stage of their existence in the 

 small globular cottony galls which abound on ger- 

 mander speedwell [Veronica chamcedrys), wild thyme 

 [Thymus serpyllum), and ground ivy [Glcchoma 

 hederacea). The latter is by no means uncommon, 

 and may be readily recognised. 



Certain species of plant-lice [Jlphydes) , whose com- 

 plete history would require a volume, produce ex- 

 crescences upon plants which may Avith some pro- 

 priety be termed galls, or semi-galls. Some of these 

 are without any aperture, whilst others are in form 

 of an inflated vesicle, with a narrow opening on the 

 under side of a leaf, and expanding (lor the most 

 part irregularly) into a rounded knob on its upper 



