No. 2368. AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 223 



rest gradually shorter to twelfth which is as broad as long, thirteenth 

 more than twice as long as preceding and partially or wholly subdi- 

 vided by a transverse groove a little back of middle. Pronotum 

 rugose. Mesoscutum shining, coriaceous with setigerous punctures 

 anteriorly but not rugose, parapsides complete but less distinct in front, 

 median nearly complete, anterior and lateral lines faintly impressed. 

 Scutellum rugoso-punctate, pits at base narrow, deep, shining, 

 smooth or with faint longitudinal ridges, triangular impressed areas 

 on sides. Propodeum with two ridges slightly bent inwardly and 

 inclosing a reticulate area broader at the top, spiracular areas and 

 petiole rugose. Mesopleura finely rugose. Hind tarsi shorter than 

 tibiae, second shorter than fifth, claws weak, simple, divergent. 

 Wings subhyaline, veins brown, first abscissa of radius faintly angled 

 and slightly clouded, areolet not reaching over one-fifth way to basal, 

 cubitus not reaching basal, surface pubescent, ciliate only on hind 

 margin of hind wing. Abdomen smooth and shining, longer than 

 high, slightly compressed, second segment occupying about two- 

 thirds and with only inconspicuous patches of hair on sides, its hind 

 margin and exposed parts of rest microscopically punctate, ventral 

 spine short, hardly longer than broad, ovipositor when dissected out 

 nearly one and two-thirds times as long as antenna. Using width of 

 head as a base, the length of mesonotum ratio is 1.2-1.3; antenna, 

 1.5-1.7; ovipositor, 1.9-2.0; wing, 3.0-3.1. 



Range in length of 77 pinned specimens, 2.8-4.8 mm. Average, 

 3.9 mm. Mode, 4.0 mm. 



Type.— Cat. No. 22569, U.S.N.M. Type and 42 paratypes. 



Host. — Quercus catesbaei Michaux, Quercus myrtifolia Willdenow, 

 Quercus texana Buckley. 



Gall. — Cells in and protruding from the brown bark at crown 

 of small trees, 5 to 10 cm. underground. When single, they are 

 elliptical in outline, sessile, 6 mm. high by 5 mm. in diameter, 

 light brown in color and smoother than the surrounding bark. Exit 

 hole 2.6 mm. in diameter at distal end. They are sometimes detach- 

 able. They often occur in rows or in groups of a dozen or more. When 

 confluent, a local swelling of the bark is produced, but the number of 

 cells contained is evident. The figure shows galls on Q. myrtifolia. 

 On Q. catesbaei they usually occur on larger roots at least 2 to 5 cm. in 

 diameter and often in the angles where branch roots arise. 



Habitat. — The type galls were collected at Marianna, Florida, Octo- 

 ber 11, 1919, on Q. catesbaei and then contained pupae. Living flies 

 were cut out of the galls on December 3. More were taken at Ocala 

 October 30, and these also contained pupae. Galls found at Ocala 

 April 15, 1914, were empty. These galls were also found at Madison 

 and Jacksonville. The species transforms inside the galls in Novem- 

 ber and probably emerges in early spring. The fact that some galls 



