PROC. ENTOMOL. SOC. WASH. 97(4), 1995. pp. 779-790 LIFE HISTORY AND DESCRIPTION OF IMMATURE STAGES OF UROPHORA TIMBERLAKEI BLANC AND FOOTE (DIPTERA: TEPHRITIDAE) ON NATIVE ASTERACEAE IN SOUTHERN CALIFORNIA Richard D. Goeden, David H. Headrick, and Jeffrey A. Teerink Department of Entomology, University of California, Riverside, California 9252L Abstract. — Urophora timberlakei Blanc and Foote is a bivoltine, probably trivoltine, tephritid which develops in the flower heads of Acamptopappiis, Amphipappus, Chryso-thamnus, and Haplopappus spp. in southern California. For the first time, the egg, second and third instar larvae, and puparium are described, and the larvae and puparium are figured. Distinctive morphological features noted for the immature stages include eggs that are smaller and of a shape different from Palearctic Urophora. The third instars resemble certain described Palearctic Urophora, but they differ from larvae of other Ne-arctic tephritids in having a bluntly truncated, dark brown to black caudal segment covered by minute dome-shaped papillae and bearing several deep pits mediad and ventrad of the posterior spiracular plates. The verruciform sensilla circumscribing the prothorax and the wedge-shaped acanthae that circumscribe the meso-, metathoracic, and abdominal seg-ments also are distinctive features. The larvae feed mainly on the ovules and soft achenes. Pupariation occurs in the larval feeding chamber among fragments of achenes. Premating and mating behaviors are described for the first time for any Nearctic Urophora, distin-guished only by the males displaying abdominal pleural distensions throughout courtship and copulation. Eupehnus sp. (Hymenoptera: Eupelmidae) is reported as a solitary, en-doparasitic, larval-pupal or pupal parasitoid. Key Words: Insecta, Urophora timberlakei, nonfrugivorous Tephritidae, mating behav-ior, immature stages, Asteraceae, flower-head feeding The genus Urophora (Diptera: Tephriti-eight introduced Old World species, were dae) is a polyphyletic assemblage of flori-reviewed and distinguished by Foote et al. vorous and/or gallicolous species of fruit (1993). Little is known about the biologies flies best known from the Palearctic Re-of the eight indigenous North American gion, where several species infesting knap-species of Urophora (Foote et al. 1993); weeds and thistles [Asteraceae: Cynareae however, all seven California species are ,r^ t ■ A r-A ■ *■ 1 M non-eallicolous, seed-feeders in flower (Centannae and Cardumae, respectively)] , , ^. . . ... ^ ... . , ..... , heads of hosts m the subtribe Solidagmmae were extensively studied and subsequently ^ , ... , . . ,^ , ^, , , ^ , . , . , or the tribe Astereae (Asteraceae) (Goeden exported to North America tor biological 1007 hf h H d t ^ control of weeds (Varley 1937, Zwolfer This"paper'detcribes the life history and 1988, Harris 1989, Julien 1992). Known immature stages of Urophora timberlakei species of New World Urophora were de-Blanc and Foote, the first North American picted in a pictorial key by Steyskal (1979), species of Urophora to be studied in any and those found North of Mexico, including detail.