No. 2368. AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 199 



segmented, antennae filiform, 13-segmented, fourth and fifth sub- 

 equal, 6-12 becoming shorter, last twice preceding with trans verse 

 suture below middle on one side incompletely separating it into two 

 parts. Mesoscutum only a trifle broader than long, smooth with 

 setigerous punctures, parapsides smooth, deep, wider behind, not 

 extending over half-way, anterior and lateral lines polished black 

 and bare. Scutellum broader than long, length 0.58 the width of 

 head, rugose with setigerous punctures, groove at base also rugose, 

 faintly margined behind. Propodeum with the median distance less 

 than the width of petiolar fossa, with a semicircular ridge above 

 petiole almost touching upper margin. Legs stout, hind femur 

 broader than coxa, tarsus shorter than tibia, second shorter than 

 fifth, claws with tooth. Wings subhyaline with distinct brown veins, 

 second cross- vein slightly clouded, first abscissa of radius angled and 

 with spur, areolet reaching about one-fifth and cubitus slightly over 

 half-way to basal, surface pubescent, margin ciliate. Abdomen 

 smooth and shining, not compressed, longer than high, second seg- 

 ment occupying three-fifths, with two large well-separated pubescent 

 patches nearly reaching hind margin on sides, ventral spine in balsam 

 tapering, over three times as long as broad, ovipositor when dissected 

 out nearly one-third longer than antenna, ovarian eggs well devel- 

 oped. Using width of head as a base, the length of mesonotum 

 ratio is 1.49; antenna, 2.6; ovipositor, 3.6; wing. 4.5. 



Length of 89 pinned specimens, 3.8-5.7 mm. Average, 4.S mm. 



Type— Oat. No. 22578, U.S.N.M. Type and 58 paratypes. 



Host. — Quercus stellata Wangenheim and Quercus margaretta Ashe. 



Gall. — Globular bullet galls up to 17 mm. in diameter in clusters on 

 runner sprouts or sprouts from stumps at surface of ground hidden 

 by loose debris. When fresh finely mottled with red, but when dry 

 almost uniformly red and finely wrinkled. Inside is a distinct thin- 

 walled central cell in the center of spongy brown tissue. 



Type locality. — Ironton, Missouri. Type galls collected on Q. 

 stellata, October 5, 1917, when a few of best developed contained 

 adults and the rest pupae. The flies issued in breeding cage out of 

 doors at Evanston, Illinois, November 6, November 11, and December 

 1, 1917, and living adults were also found in cage February 19 and 

 March 11, 1918. Galls were also collected at Poplar Bluff, Missouri, 

 October 8, 1917, and 18 flies were found alive in cage on December 

 IS, the thermometer having registered — 14° F. on December 10. 

 Collected galls at Webster Groves, Missouri, September 9, 1915, and 

 cut out living adults November 2. Have collected these galls also 

 at Hoxie, Hot Springs, and Texarkana, Arkansas; and at Palestine 

 and Trinity, Texas; Dothan, Alabama; Marianna, Tallahassee and 

 Madison, Florida — all on Q. stellata. In the United States National 

 Museum are galls from Shovel Mount, Texas, collected by F. G. 



