Gall - Midge (Fly) - Rhopalomyia baccharis - Rhopalomyia baccharis
San Jose/Alum Rock Park, Santa Clara County, California, USA March 1, 2007 Size: 5 cm x ~7 mm
A.k.a. Coyote Brush (Baccharis pilularis) Twisted Stem Gall (Midge). Species confirmed by Ron Russo, author of Field Guide to Plant Galls of California and Other Western States (ISBN 0520248864); see page 240.