318 AMERICAN HYMENOPTERA. 



following from <l;irk to dull brown, nearly black at the apex. Thorax black, 

 space between the very deep parapsidal grooves elevated and shining, though 

 minutely uneven or punctate between the parapsides, at the collare are two very 

 black round spots. Scutellum small, finely uneven or rugose. Fovse — if such 

 they can be called — widely separated and hardly more than a less roughened and 

 very shallow depression. Abdomeu polished, black, first segment large and 

 with a few extremely minute hairs on the sides of the anterior half of this seg- 

 ment. Legs clear, trauslucent brown. Wings large, faintly fuscous, hairy. 

 Veins rather heavy. Areolet distinct. Cubitus disappearing close to the first 

 transverse. Areolet open, angles at its base, one sharply acute, the other corres- 

 pondingly obtuse. Body .09, wings .11, antennae .07. 



From East Rock, New Haven, Conn. 



AudriciiK exiguiiM n. sp. 



Visiting West Rock, near New Haven, Conn., several years ago 

 in June, I found among the dry but still adherent aments of Q. 

 obtusiloba a number of very minute, dark colored, oval galls. The 

 insects had escaped, but the species was new to me. Three or four 

 years later i visited the locality in May and found galls in abund- 

 ance, and the flies were very*near maturity. I collected plenty of 

 galls by breaking off small flower-covered branches. Placing these 

 in water and keeping them under glass, a large number of very 

 small gall-flies soon appeared. The galls were thin, short, oval 

 larval cells, merely the modified sterile florets of the oak. Of galls 

 affecting the sterile flowers of different kinds of oaks there are 

 several species, but these were smaller and otherwise different from 

 any I had seen. The effect of the sting of the fly was often to 

 check the extension of the floral stems to a degree that reduced the 

 florets to a close bunch or mass. This glomerate condition did not 

 prevent the development of the gall-flies, and probably ten times as 

 many flies appeared as there were galls in sight These galls are 

 hardly black, but rather of a very dark slate color; they are not 

 quite smooth. In size they measure nearly .05 of an inch in length 

 and almost .04 in breadth. The apex is bluntly pointed. They 

 are so very thin shelled and brittle that it is almost impossible to 

 remove one when dry from the anient to which it is attached. After 

 rearing several thousand flies from these galls I noticed that there 

 were at least two species in the box. They differed little in size or 

 general appearance as viewed with the naked eye, but the magnify- 

 ing glass showed that there were two genera. I examined the galls 

 very carefully, but found but a single species, and from this the 

 Andricus surely came, as I found a specimen in the unopened galls. 



