LIFE-HISTORY AND DESCRIPTION OF IMMATURE STAGES OF PAROXYNA-GENALIS (THOMSON) (DIPTERA, TEPHRITIDAE) ON NATIVE ASTERACEAE IN SOUTHERN CALIFORNIA

Paroxyna genalis (Thomson) is a multivoltine tephritid that develops in flower heads of a broad spectrum of Asteraceae in California. The egg, first through third-instar larvae, and puparium are described and figured for the first time. Distinctive morphological differences noted for these immature stages are in the sensilla comprising the lateral spiracular complexes of the meso- and metathorax and in the distribution and incidence of rugose pads on the anterior of the prothorax of the third instar larva. The larvae feed mainly on the ovules and soft achenes, but also may score the receptacle and imbibe sap at fresh wounds in these structures. Pupariation occurs in the larval feeding chamber among fragments of scored achenes. Premating and mating behaviors are described, including a characteristic, uplifted-wing movement newly designated as ''lofting.'' Mate-guarding behavior by males following copulation is reported, apparently the first example among Holarctic Tephritidae. The principal natural enemies of immature P. genalis were the solitary, primary, larval-pupal, endoparasitic, chalcidoid Hymenoptera, Eurytoma sp. (Eurytomidae) and Pteromalus sp. (Pteromalidae).