DESCRIPTIONS OF OAK-GALLS. 



225 



of these we know comparatively nothing. When tlie whole 

 life and surroundings of a single gall-fly can be written, it 

 will doubtless be found to bear directly on many disputed or 

 little understood points of entomological knowledge gene- 

 rally. But nothing can be done without breeding; and 

 when the gall species is correctly determined the gall-maker 

 is easily recognised. For some remarks on the breeding of 

 gall-flies, see the 'Entomologist,' viii. 170, The study of the 

 flies themselves is at present difficult and unsatisfactory ; the 

 descriptions may be referred to in the papers mentioned 

 above ; and there is a synopsis of genera, by Dr. Forster, in 

 the nineteenth volume of the Vienna ' Verhandlungen' (1869). 



Two new European oak species have been described 

 since the appearance of Dr. Mayr's work, viz. : — Andricus 

 Sclirockiugeri, Wachtl. (Verb. z.-b. Gesell. Wien. xxvi. 713), 

 which causes a gall on the leaf of Quercus cerris something 

 like that of S. albipes ; and AphUothrix Kirchsbergi, 

 Wachtl. (Verb. z.-b. Gesell. Wien. xxvi. 713). This last is 

 the Cynips gemmea, Gir., which was figured in the 'Ento- 

 mologist,' ix. 78. 



The following is a list of our British oak species as far as 

 our present knowledge goes, giving the name of species in 

 the first column, reference to the gall in the second, the 

 time of appearance of the gall in the third, the time of 

 appearance of the gall-fly in the fourth, and the reference to 

 the description and figure in the last : — 



2 b 



