Spathegaster albipes. 19 



way as with the former species, and have frequently 

 succeeded in getting the flies to prick the small oaks. 

 The first accurate experiments were made in March, 

 1875. Between March 14 and 26, thirty-six buds in 

 all were pricked by a large number of flies. On the 

 unfolding leaves there appeared in May the gall of 

 a totally different fly, Spathegaster albipes. From the 

 strict control exercised there could be no doubt that 

 these galls proceeded from Neuroterus laeviuscnlus. 

 From my first experiment I obtained thirty-six galls, 

 but from others made in 1877 I only got two galls. As 

 a rule experiments made with these flies are pretty 

 certain to succeed. 



[The smooth spangle gall is found on Q. pedunculata. 

 Inquiline. Synergus Tscheki in April. 



Parasites. Toryrnns sodaJis in March and April. T. hibenians. 

 The spangle galls live about nine months.] 



2=^. Spathegaster albipes. Schenck^ 



Gall. Size, 1-2 mm. in length; oval with a short apical 

 point, of a greenish yellow colour, smooth or thinly set 

 with solitary hairs. The galls are sessile on the leaves, 

 which they deform more or less, causing indentations or 

 sinuosities and often stunting them in their growth. 

 This is due to the mode of origin of the gall which is 

 formed on the rudimentary leaf while yet in the bud. 

 The area occupied by the gall in the bud is of course 

 small, but the effect upon the leaf when it expands is 

 much more marked. (Fig. 2'"^.) 



Fly. Size, 1-2 mm. long; black ; thorax smooth 



\} Neuroterus laeviusculus, sexual form, Cameron. Neuroterus albipes 

 Mayr.] 



C 2 



