GENUS ANDRICUS. 75 



The genus contains some undoubted agamic species. 

 The sexual forms have, with the exception of A. inflator 

 and A. curvator, the antennas 13-jointed; the last- 

 mentioned having them 14-jointed. They are further 

 to be known from most of the agamic species by 

 having the mesonotum, especially posteriorly, very 

 shining and glabrous, at the best having only the 

 centre of the mesonotum slightly pilose. With two 

 exceptions {amenti and ramuli) they are black, with 

 the legs more or less dark, light, or citron yellow. As 

 usual, the spring forms are much smaller than the 

 agamic. These have the antennae 13 — 15-jointed; 

 few, however, of our species having them 13-, and none 

 15-jointed. Some of them, e. g. glandulse, albopunc- 

 tata, Gollaris, have the mesonotum glabrous and shining 

 as in the sexual forms. Yery few are entirely black, 

 and many of them are very variable in coloration. 

 In both forms the head may be widened behind the 

 eyes. 



Generally this and the following genera (the oak- 

 frequenting species) are to be known from the pre- 

 ceding by the cheeks being at least half as long as the 

 eyes, while the radial cellule is much narrower and 

 longer. 



It is worthy of remark that at Kew Gardens two 

 species are found on the Turkey oak (Quercus cerris), 

 these species neither here nor on the Continent being 

 known to frequent Q. robur. As Q. cerris is an im- 

 ported tree, not native, it may be presumed that the 

 gall-flies have been introduced in some way also. 



A. Claws simple; mesonotum transversely rugulose 



(Species 1). 



