HYMENOPTERA OAK GALLS. 



141 



2a. Spathegaster tricolor (Htg.) 



The sexual species forms a pea-shaped hairy gall of light-yellowisli- 

 green colour (fig. 136), appearing about the end of June or beginning of 

 July. They are found in clusters 



on the under side of tlu: 

 The hairs fall off wl 

 gall matures, and then 



Spathegaster 

 however, is 



Fig. 



Galh of Neuroterus lajviusculus. 



be mistaken for 

 haccarum, wliich, 

 over by this time. 



The fly is a very slender 

 insect, the wings when spread 

 out being comparatively long 

 in proportion to the body. 

 The body is about 2 mm. long, and the expanse of wings 8 mm. 

 The body is black throughout, legs all yellow, and the wind's 

 rather cloudy. Males and females very much 

 alike. 



3. Xeuroterus L/Eviusculus (Scheuck.) 



This gall (fig. 137) is very much like th(i 

 two previous species in general appearance, 

 but not so common or so numerous on the 

 leaf. The form is similar, but in tliis 

 species the gall is nearly smooth excejit on 

 a well-defined knob in the centre, wliich is 

 covered with hairs. I have not reared the 

 fly, but found the gall fairly common botli 

 in Cheshire and Northumberland. 



3r<. Spathegaster albipes (Schenck.) 



ig. \Z%.~(kdls of Spathe- 

 g.-istor albipes. (Drawn by 

 P. .J. Brown.) 



This is the agamic species of N. Idivlusrulus 

 and I have only found it in one district — 



viz., at Pauperhaugh, in Northumberland, about tlie Ijeginning of 

 June. The gall of this species (fig. 138) is more or less oval, tapering 

 to a blunt point, and of a slightly yellowish-green colour. The gaUs 



