102 THE CANALJIAN ENTOMOLOGIST. 



leaves of Qnercus bicolor, rarely more than one on a leaf. The pedicels 

 are from one-half to three-fourths of an inch long. The galls are three- 

 eighths long and one-eighth of an inch in diameter, oval and resemble 

 very closely the capsules of certain mosses. Surface rough, and with the 

 pedicel finely pilose, or rather, pubescent. The pedicel is usually, but 

 not invariably, the extension of a lateral leaf vein. The whole is of the 

 color of the under side of the leaves of this species of oak. Most of the 

 leaves which bear galls are fully developed, but a part are more or less 

 imperfect and occasionally a gall is found on what is but the merest rudi- 

 ment of a leaf. 



The galls appear with the leaves and the insects come out early in 

 June. This little gall is a true larval cell and its thin walls offer slight 

 obstacle to the attacks of parasites. 



The gall flies are of both sexes and are described as follows : 

 Female : Color a deep shining black, with the exception of the 

 antennae, legs and sheath of the ovipositor. Head and thorax microsco- 

 pically punctate and sparsely dotted with extremely fine, short hairs. 

 Parapsidal grooves : One pair converging as they approach the scutellum, 

 and a slight groove over the base of the wings. The short parallel pair 

 seen in many species near the dorsal line is in this species represented by 

 a very slight depression on each side of the rather prominent dorsal ridge, 

 but these last are so obscure as to easily escape notice. The scutellum 

 wrinkled rather than punctate. Fovse wanting. Antennae short, 13- 

 jointed, ist and 2nd globose, 13th as long as the nth and 12th together 

 and with a connate suture. Color amber, inclining to brown. Legs : 

 Coxae, trochanter black or blackish brown, femur and tibia dark, clear 

 shining brown, paler at the joints. Tarsi pale cinnamon brown. Ungues 

 black. Wings h3'aline, veins pale brown, fading in the smaller ones to 

 hyaline. Areolet small, indistinct. Radial area short, broad, open. 



Abdomen : ist segment equal in length to all the others taken 

 together. The sheath of the ovipositor dark translucent brown, not 

 turned up at the extremity. 



Length, body .10, wing .11, antennas .06. 



Male : The smaller size, darker and longer antennee, darker legs, and 

 the much smaller and laterally compressed abdomen distinguish the male 

 from the female. 



Length, body .07, wing .11, antennae .08. 

 Described from dry specimens in my collection. 



