Biorhiza caepuliformis
Andricus caepuliformis
The galls of this species occur singly or in clusters of as many as 30 at the base of young vigorous saplings or sprouts from stumps, usually hidden by debris and often inclosed in a cylindrical case 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, Winnetka, Evanston, River Grove, Glenn Ellyn, Willow Springs, and New Lenox, Illinois, and at Tuskahoma, Oklahoma; on Q. marilandica Muenchhausen at Hot Springs, Arkansas; Palestine, Texas; and Marianna, Florida. On Q. texana [buckleyi] Buckley at Boerne and Kerrville, Texas. On Q. falcata Michaux at Dothan, Alabama. On Q. laurifolia Michaux at Daytona and Gainesville, Florida. On Q. catesbaei [laevis] Michaux at Marianna, Florida. On Q. brevifolia Sargent at Marianna, Madison, Jacksonville, Ocala, and Gainesville, Florida. On Q. myrtifolia 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 galls are largest on Q. rubra.
