H. F. BASSETT. 315 



in the galls had undergone no change. A few individuals emerged 

 from the galls in the Winter, though most remained alive in the 

 galls many months after. 



Gall-flies all females. Entire insect dark reddish brown. Head microscopi- 

 cally punctate. Antenna; fourteen jointed, first of moderate length, second 

 short, ovate, third one-third longer than the first two, fourth to the seventh 

 gradually shorter, the following short and ovate. Thorax smooth, shining, 

 mesothorax with broad, deep parapsidal grooves. Scutellum subquadrate, finely 

 rugose; fova? broad, distinct, the carina small, but extending to the posterior 

 margin of the scutellum. Abdomen large, compressed laterally so as to give to 

 the dorsal and ventral edges a knife-like sharpness, it is entirely smooth, except 

 a few minute hairs on the sides of one of the terminal segments (the last but one). 

 Legs less dark than the rest of the body. Wings large, veins distinct. Areolet 

 obsolete or nearly so, reduced to a very small light spot at the crossing of the 

 heavy veins. Cubitus extends almost to the first transverse. Radial area open, 

 its broad basal vein stopping abruptly at a distance from the costal border. Body 

 .14, antenna .10, wings .16. 



The extremely slow development of this species gave an oppor- 

 tunity to study the changes as they took place 



V imI i'i«'ii» operatola Riley and Bassett (Manuscript ?). 



I cannot find that Prof. C. V. Riley ever published a full de- 

 scription of this gall and gall-fly, and this is, undoubtedly, the 

 agamous form of operator O. S., to which he gave the manu- 

 script name above given. He reared the gall-fly from galls which 

 he and myself collected near my home in Waterbury, Conn., in the 

 Autumn, and the next Spring he sent me specimens of the flies 

 which he had reared, and he referred to the species in different 

 writings, I think. But nothing, so far as I can learn, like a full 

 description has ever been published. I have written a full account 

 of the discovery of A. operator ovipositing in the acorns and of the 

 development of the galls therefrom, which was published in the 

 Proc. Ent. Soc. Phila., in 1864; but I give here only the characters 

 necessary to its identification. The galls are produced from the 

 eggs of A. operator O S., who deposits them at or near the base of 

 the young acorns of Q. ilicifolia. The ovipositor is thrust down 

 between the acorn and the acorn cup, and in due time the gall is 

 developed. The galls reminds one of the pseud chestnuts that are 

 often seen in the chestnut burrs, being flattened and rarely approach- 

 ing the shape of an acorn. From one to five or six of these are 

 found in an acorn and they vary greatly in size, from that of a flax- 

 seed to one-third of an inch in length. The acorn is, in most case-, 



TKANS. AM. ENT. SOC. XXVI. JULY, 1900. 



