HYMENOPTERA OAK GALLS. 



145 



Fig. 137. Galls o/Neuroterus Laeviusculus. 



2a. Spathegaster tricolor (Htg.) 



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

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

 July. They are found in clusters 

 on the under side of the leases. 

 The hairs fall off when the 

 gall matures, and then it may 

 be mistaken for Spathegaster 

 haccarum, which, however, is 

 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 wings 

 rather cloudy. Males and females very much 

 alike. 



3. Neuroterus l^eviusculus (Schenck.) 



This gall (fig. 137) is very much like the 

 two previous species in general appearance, 

 but not so common or so numerous on the 

 leaf. The form is similar, but in this 

 species the gall is nearly smooth except on 

 a well-defined knob in the centre, which is 

 covered with hairs. I have not reared the 

 fly, but found the gall fairly common both 

 in Cheshire and Northumberland. 



3a. Spathegaster albipes (Schenck.) 



Fig. 138. Galls of Spathe- 



This is the agamic species of N. lce.viuscv.lus, f^B^nl' (Drawn by 

 and I have only found it in one district 



viz., at Pauperhaugh, in Northumberland, about the beginning 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 galls 



