Urophora solstitialis. 



The gall formed by this species is one of the most perfectly- 

 concealed it is possible to imagine. The flower is not altered 

 in colour, nor is the head itself enlarged. The gall is situated 

 in the centre and in the base of the flower-head, completely 

 obscured by the florets. Its presence can be ascertained only 

 by removing some of the florets, or by squeezing the head 

 between finger and thumb, when a hard substance will be 

 felt. It is extremely hard and woody ; and is almost covered 

 with long, silvery hairs, mostly about 8 mm. long, which under 

 magnification are seen to be tubular at the point of attachment, 

 but fasciated at the latter third of their length, and freely 

 branched. The larval chambers are arranged parallel with each 

 other, with an opening at the apex of the gall-structure. In 

 October the larvze pupate. The pupal skin, which is cylindrical, 

 has a flat top, with a hard, black circular shield upon it, exactly 

 fitting the circumference of the portion of the cell-tube 

 surrounding it. This, doubtless, acts as a defence against 

 parasites and other intruders. 



The illustration is of specimens gathered at Hastings by 

 the author. 



