PROC. ENTOMOL. SOC. WASH. 99(4), 1997. pp. 748-755 LIFE HISTORY AND DESCRIPTION OF IMMATURE STAGES OF TRUPANEA SIGN ATA FOOTE (DIPTERA: TEPHRITIDAE) ON GNAPHALIUM LUTEO-ALBUM L. IN SOUTHERN CALIFORNIA Richard D. Goeden and Jeffrey A. Teerink Department of Entomology, University of California, Riverside, CA 92521, U.S.A. Abstract. — Trupanea signata L. is a narrowly oligophagous, multivoltine, gregarious, obligately gallicolous fruit fly (Diptera: Tephritidae) studied in southern California on Gnaphaliiim luteo-albiim L. This host plant is an introduced weedy annual of Old World origin to which this tephritid has transferred from indigenous, congeneric hosts, an un-common occurrence among nonfrugivorous North American Tephritidae. The egg, third-instar larva, and puparium are described and figured. The eggs are inserted into apical and axillary buds. From one to six larvae feed gregariously within an open cavity in the expanded pith parenchyma of galls on axillary branches and stems during all three instars. The galls are elongate-obclavoidal, sometimes bear axillary branches and flower heads, and are covered by a wooly investiture. Pupariation occurs inside the gall. The adults emerge and exit the gall through a common channel by pushing aside a thin, pre-formed, apical, "gall cap." The adults are long-lived and are the overwintering stage. The life cycle follows the aggregative pattern and at least two generations, one each in spring and fall, are produced annually on G. hiteo-album. Two species of solitary, larval-pupal, hy-menopterous endoparasitoids are reported: Eurytoma sp. (Eurytomidae) and Pteromalus sp. (Pteromalidae). Key Words: Insecta, Trupanea, Gnaphalium, biology, taxonomy of immature stages, galls, oligophagy, parasitoids The genus Trupanea (Diptera: Tephriti-immature stages of three of these species dae) occurs worldwide and is a numerically also described (Cavender and Goeden 1982, large and widespread taxon of nonfrugivo-Headrick and Goeden 1991, Knio et al. rous fruit flies in North America and Cali-1996a). This and our next five papers will fornia (Foote and Blanc 1963, Foote et al. more than double the number of species of 1993). As such, the adults are among the Trupanea for which life histories and im-most commonly encountered, reared or mature stages are well known, beginning swept tephritids; however, the life histories here with the indigenous, obligate gall-for-of most species remain little known, and ^^^^^ ^-^^8^^^^^ Foote. several species are difficult to distinguish morphologically (Foote 1960, Foote et al. 1993). Detailed life histories of five species Our field studies on T signata mainly fo-of Trupanea from southern California have cused on laboratory dissections of galls col-been published (Cavender and Goeden lected on Gnaphalium luteo-album L. at 1982, Goeden 1987, 1988, Headrick and different locations in central and southern Goeden 1991, Knio et al. 1996b), and the California during 1989-91: (1) N end of Materials and Methods
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