No. 2368. AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 207 



made by ants about the cluster, as the galls give off an exudate 

 when young of which the ants are fond. They burst out through a 

 crack in the bark and when detached leave a characteristic cup- 

 shaped cavity in the bark. Fresh galls are full grown about Chicago 

 by August 1 and contain pupae by September 12 and the adults by 

 October 3. In breeding, cages the flies emerged November 23-26 

 and in greater numbers by December 2. In Florida pupae were seen 

 October 10, 17, and 23, the earliest adults in the galls November 20 

 and the earliest emergence was December 1. The alternating 

 generation is unknown. 



The species was originally described from Quercus velutina Lamarck 

 from Indiana. The writer has taken it on Q. velutina at Poplar Bluff 

 and Ironton, Missouri; Hot Springs and Texarkana, Arkansas; and 

 Falls Church, Virginia. He has also taken it on eight other host oaks 

 as follows: On Q. rubra Linnaeus at Fort Sheridan, Ravinia, Win- 

 netka, Evanston, River Grove, Glenn Ellyn, Willow Springs, and 

 New Lenox, Illinois, and at Tuskahoma, Oklahoma; on Q. mari- 

 landica Muenchhausen at Hot Springs, Arkansas; Palestine, Texas; 

 and Marianna, Florida. On Q. texana Buckley at Boerne and Kerrville, 

 Texas. On Q. falcata Michaux at Dothan, Alabama. On Q. lauri- 

 folia Michaux at Daytona and Gainesville, Florida. On Q. catesbaei 

 Michaux at Marianna, Florida. On Q. brevifolia Sargent at Marianna, 

 Madison, Jacksonville, Ocala, and Gainesville, Florida. On Q. myrti- 

 folia Willdenow at Carrabelle and Daytona, Florida. About Chicago 

 these galls seem to be much more abundant some seasons than others. 



From these galls come only agamic females. The antennae were 

 described as 14-segmented. In this case the last is one and three- 

 fourths times the preceding and often bears a more or less distinct 

 transverse suture so that it is sometimes 15-segmented. The galls 

 are largest on Q. rubra, and 30 flies from these galls in writer's col- 

 lection measure 3.9-5.2 mm. Average, 4.6 mm. Using width of 

 head as a base, the length of mesonotum ratio is 1.0; antenna, 2.7- 

 2.9; ovipositor, 4.3-4.7; wing, 2.5-2.6. Ten flies from Q. laurifolia 

 galls measure 3.6-4.2 mm. Average, 3.9 mm. 



12. BIORHIZA OCALA, new species. 



Female. — Head, thorax, and flagellum black; rest of body red- 

 dish-brown. Head broader than high, as broad as thorax, cheeks 

 not wider than eyes, malar space about 0.3 eye and without furrow, 

 palpi 5- and 3-segmented, antennae 14-segmented, third longest, 

 fourth 0.7-0.8 third and equal to 1 plus 2, fifth 0.6 third, last one and 

 one-half times preceding, distal third tapering to tip, mandibles 

 three-toothed. Interocular area as broad as high. Mesoscutum 

 smooth and shining with two complete, narrow, smooth parapsides 



