NORTH AMERICAN HYMENOPTERA. 81) 



3. 1^. pallipes ii. sp. 



Galls small, monothalamous, variously situated on the stem and 

 principal veins of very young white oak leaves, dwarfing and dis- 

 torting them, and densely covered and often nearly hidden in their 

 pubescence. They are oval, thin walled, and only large enough to 

 contain the larva of the small gall-fly. 



I have forty male and female insects of this species, hut there is 

 only one, a female, whose antennoe remains unbroken. 



Gall-flies. — Both sexes are black and shining; the female anteiinai with thir- 

 teen joints, and, like most of this genus, the first two joints very large, short, 

 almost globose, and the rest long and slender; they are pale brown at the base, 

 growing dusky towards the tips; the third joint is scarcely longer than the 

 fourth ; the male abdomen long, petiolated ; the winjjs of both sexes large; the 

 veins distinct, but not heavy ; areolet large, and bounded by very slender veins, 

 cubitus reaching the tirst transverse vein, radial area open, long and narrow ; the 

 legs in the female almost colorless, and in the male brown or brownish in the 

 middle of the tibia and femur only. Length : body, .05 inch. ; wings, .06 inch. 



The insects differ materially from N. utrimda Bass., though the 

 galls resemble those quite nearly. 



This species was received from Miss Cora A. Clarke, to whom I 

 am indebted for several other very interesting species. 



4. IV. politus n. sp. 



The galls are developed on the midvein of the leaves Q. undulata ? 

 and are three-fourths of an inch long and half as thick. They are 

 polythalamous ; larval cells perpendicular to the surface of the leaf. 

 They might easily be taken for galls of Andricus nigne, A. tinnifica 

 and other species found on the midvein of oak leaves, but the insects 

 are distinct from any produced from similar galls. 



Gall-fly. — Male. — Head black ; anteunse fourteen jointed, first and second 

 joints pale yellow, remaining ones yellowish brown, all very slender. Thorax 

 without furrows or grooves; thorax and abdomen black and very smooth ; scu- 

 telluni separated from the mesothorax by a smooth, shining furrow; a few scat- 

 tered hairs on the posterior half of the scutellum. Abdomen long petiolated, 

 second segment small, the remaining ones very small. Legs pale yellow. Wings 

 large, veins brown, slender, the cubitus reaching the first transverse and of ecjual 

 size throughont, areolet very small, radial area large, long and open. 



My few specimens, cut from the galls, are too imperfect to furnish 

 a more complete description. One of them, apparently a female, is 

 considerably larger and with darker antennse and legs, but I will 

 not attempt a description from it. 



The galls were found with those of Andricus Sileri from southern 

 Utah. 



TRANS. AM. ENT. SOC. XVII. (12) MAKCH, 1890. 



