366 



FOREST ENTOMOLOGY. 



DiPLOSIS (HaRMAXDIa) TREMUL/E, Wtz. 



Theobald says: "The larvie of the 'aspen gnat' seem to form two 

 kinds of galls : the first are formed on the leaves of Populus treinida — 

 these are red galls, the size of a pea ; the second kind is the well- 

 known gall formed on the leaf-stalk : each gall is inhabited by a 

 single larva, which pupates in the ground (Winnertz)." ^ 



I found what I now suspect to have been the first form, in June 

 1897, in High Legh, Cheshire, but the latter I have never found, and 

 am indebted to Mr E. T. Connold for the form as shown in fig. 337. 



Theobald thus describes the tly : " Imago — dorsum l)lackish-brown, 

 with two rows of whitish-yellow hairs ; abdomen dark -brown, with 

 thin flesh - coloured incisions and white hair. Posterior half of 

 seventh ring and the rest of the abdomen flesh-coloured ; $ genitaHa 

 black ; ^ yellow. M^'ings large, grey, with thick blackish-grey hairs, 

 third longitudinal vein bending in an almost straight angle to the 

 posterior edge; 1 to 1| lin." 



I An Account of British Flies, by Fred. V. Theobald, p. 7.''). 



