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 i n flower heads of a broad spectrum of Asteraceae in California. The eg g, first through third-instar larvae, and puparium are described and f igured 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 distributi on and incidence of rugose pads on the anterior of the prothorax of th e third instar larva. The larvae feed mainly on the ovules and soft ac henes, but also may score the receptacle and imbibe sap at fresh wound s in these structures. Pupariation occurs in the larval feeding chambe r among fragments of scored achenes. Premating and mating behaviors ar e described, including a characteristic, uplifted-wing movement newly designated as ''lofting.'' Mate-guarding behavior by males following c opulation is reported, apparently the first example among Holarctic Te phritidae. The principal natural enemies of immature P. genalis were t he solitary, primary, larval-pupal, endoparasitic, chalcidoid Hymenopt era, Eurytoma sp. (Eurytomidae) and Pteromalus sp. (Pteromalidae).