Pest Fruit Flies of the World
Dacus tsuneonis Miyake, Dacus cheni Chao
Japanese orange fly.
Body. Body predominantly orangish to brown.
Head. Number of frontal bristles two pairs (usually), or three pairs. Number of orbital bristles one pair. Anterior orbital bristle of male normal, unmodified. Posterior orbital bristles reclinate; acuminate. Ocellar bristles absent or minute, like setulae. Postocellar bristles absent. With both inner and outer vertical bristles. Outer vertical, postvertical and postocellar bristles all acuminate. Postocular bristles acuminate; reduced in number and size, hardly detectable in 25x. Genal bristle present. Head higher than long. Male and female head width the same. Frontofacial angle about equal to a right angle and angular. Face flat, or undulating, convex above, concave below; with distinct antennal grooves and carina; shorter than frons; vertical; with dark spots in antennal furrows (elongate oval). Parafacial spot absent. Frons and parafacial without small silvery markings. Fronto-orbital plate setulose. Frontal stripe setulose. Eye elongate, considerably higher than long. Antenna about as long as face, or considerably longer than face. Scape, pedicel, and first flagellomere scape and pedicel short, first flagellomere elongate. First flagellomere as long as face; rounded apically. Arista longer than first flagellomere; bare or with hairs distinctly shorter than greatest aristal width. Proboscis short, capitate.
Thorax. Inner scapular bristle present and distinguishable from surrounding vestiture; dark. Outer scapular bristle present and distinguishable from surrounding vestiture; dark. Postpronotal bristle absent. Presutural dorsocentral bristle absent. Presutural supra-alar bristle absent. Postsutural supra-alar bristle present (supernumeraries may be present). Acrostichal bristle absent. Postsutural dorsocentral bristle absent. Intra-alar bristle present, well developed, similar to postalar bristle. Intrapostalar bristles absent. Number of scutellar bristles one pair. The single pair of scutellar bristles apical. Anterior notopleural bristle present. Posterior notopleural bristle(s) acuminate. Number of outstanding anepisternal bristles one. Katepisternal bristles absent. Anepisternal bristles dark, brown to black. Long, erect setulae on laterotergite absent. Scutal setulae acuminate and pale. Scutellum densely setulose. Setulae on scutellum short, decumbent; unicolorous, acuminate. Transverse suture with the lateral branches wide apart. Complete sclerotized postcoxal metathoracic bridge present. Scutum orange-brown, or red-brown; without a large dark central stripe which broadens basally. Postpronotal lobe entirely pale whitish or yellowish; concolorous with lateral postsutural stripe. Posterior half of notopleuron pale whitish or yellowish, or same as ground color. Scutum dorsad of notopleuron with a pale whitish or yellowish stripe which extends from postpronotal lobe to posterior half of notopleuron, or with a pale stripe which extends from the postpronotal lobe dorsad of the darker anterior notopleuron, and over posterior part of posterior notopleuron. Dark lyre-like pattern on scutum absent. Discrete shiny black spots on scutum absent. Median longitudinal black stripe on scutum absent. Number of pale whitish to yellow postsutural stripes three. Pale medial postsutural stripe of scutum tear-drop shaped, or wedge-shaped. Lateral postsutural stripes of scutum extending to intra-alar bristles or beyond. Scutum without blackish dorsocentral stripe. Area bordering scutoscutellar suture medially without dark brown spot, light colored. Discrete pale horizontal stripe along upper anepisternum absent or indistinct. Distinct pale vertical anepisternal stripe extending to anterior notopleural bristle. Katepisternite with pale yellowish or whitish spot present and distinct. Transverse suture without distinct stripe or spot. Katatergite with pale yellowish or whitish spot present and distinct. Anatergite with pale yellowish or whitish spot present and distinct. Subscutellum uniformly brown. Mediotergite uniformly brown, or yellowish to orange-brown medially, with distinct dark spots laterally. Scutum entirely microtrichose, microtrichia evenly distributed, or at most with small presutural, medial bare area, or microtrichia in discrete pattern due to density differences. Dorsum of scutellum flat or slightly convex, not swollen. Scutellum normal; without a dark and pale pattern (at most a narrow dark basal line); with no isolated dark spots; without black mark; without mark (yellow-brown (brown in middle) to brown).
Legs. Femora slender. Fore femur without bristles; without ventral spines; without major bristles. Mid femur and hind femur without spine-like bristles. Middle leg of male without feathering. Femora all entirely of one color; dark mark on fore femur 0% of length of femur; dark mark on middle femur 0% of length of femur; dark mark on hind femur 0% of length of femur.
Wings. Wing partly bare. Cell bc microtrichia absent, or present in apical area only. Cell c microtrichia present in apical area. Cell dm bare on less than basal one-third. Dense microtrichia at end of vein A1+CuA2 in male present. Dominant wing pattern costal-banded. Wing pattern mostly yellowish, or mostly brownish. Dark longitudinal streaks through basal cells absent. Costal band colored from Sc to beyond R4+5, or complete from wing base to beyond R4+5. Apex of costal band distinctly expanded into a spot, or not distinctly expanded. Costal band reaching R4+5 (pale); pale, but darker at apex giving appearance of an apical spot, or pterostigma darker. Crossvein r-m hyaline. Crossvein dm-cu hyaline. Crossveins r-m and dm-cu not both covered by a single crossband. Cell r2+3 apical to r-m entirely infuscated. Anal band present, reaching nearly to wing margin along cell cup extension (faint apically). Cell r1 and r2+3 with distinctly darker spots within dark areas of pattern. Intercalary band absent. Subbasal crossband absent. Marginal hyaline area in cell r1 absent or indistinct. Ratio of width of apical band in cell r4+5 to length of r-m 0.33–0.5. Anterior apical crossband contiguous with costa over entire length, without marginal hyaline band or spots apically in cells r1 and r2+3. Anterior apical band or costal band not extended to vein M. Posterior apical crossband absent. Outstanding costal spine(s) at subcostal break absent. Ratio of length of costal section 3 to costal section 4 0.8. Ratio of pterostigmal length to width 7. Vein R1 dorsal setation without bare section opposite end of vein Sc. Vein Rs dorsal setation non-setulose. Vein R2+3 generally straight. Anteriorly-directed accessory vein emerging from R2+3 absent. Vein R4+5 dorsal setation dense over at least proximal section; ventral setation present. Distance between crossvein r-m and costa equal to r-m. R-m crossvein on cell dm at or near distal third of cell dm. Cell bm broad, parallel-sided; ratio of length to width 3; ratio of width to cell cup width 2. Vein M distally straight. Cell dm widens apically gradually from base. Posterodistal corner of cell dm approximately a right angle, or distinctly obtuse. Cell cup extension or lobe present, vein CuA2 abruptly bent; longer than vein A1+CuA2; with parallel margins.
Abdomen. Abdomen petiolate. Abdominal tergites separate. Abdomen in lateral view arched, dome-like, rather rigid. Abdominal tergite 1 broader at apex than at base; without a prominent hump laterally. Pecten of dark bristles on tergite 3 of male present. Tergal glands on tergite 5 present. Abdominal tergite 5 normal. 6th tergite of female normally concealed; shorter than 5th. Abdominal setulae acuminate and pale. Abdominal microtomentum uniform, or absent. Posterior margin of sternite 5 of male with deep V-shaped posterior concavity (IMW). Abdominal tergites 3–5 predominantly yellow to orange brown. Abdominal tergites with medial dark stripe on T3-T5 and a transverse dark line on T3; not brown with medial T-shaped yellow mark; with separate dark areas on anterolateral margins of T3-T5, or without isolated dark areas on lateral margins of T3-T5; with dark brown transverse bands which may be interrupted medially.
Male terminalia. Epandrium in posterior view with moderately long outer surstyli, which are up to about half as long as epandrium; lateral view with outer surstyli distinctly narrower than epandrium, clearly differentiated.
Female terminalia. Syntergosternite 7 straight; shorter than preabdomen; base without a laterally projecting flap; bottle-shaped. Ratio of syntergosternite 7 to abdominal tergite 5 2–3. Dorsobasal scales of eversible membrane about as large as other scales. Aculeus tip pointed, with preapical shoulder, or trilobed; fused to main part of aculeus, not movable; not serrate, or with large, coarse serrations. Two sclerotized spermathecae. Spermathecae tight-set coils.
Miscellaneous. Male attractant: none known.
Palearctic, Oriental. Japan (Kyushu, Ryukyu Is.), China (Sichuan, Guangxi, Guizhou; Hunan, Jiangsu?).
Illustrations. • Habitus female (dorsal), wing, female terminalia. • Habitus female (dorsal), wing.
Cite this publication as: ‘L.E. Carroll, I.M. White, A. Freidberg, A.L. Norrbom, M.J. Dallwitz, and F.C. Thompson. 2002 onwards. Pest fruit flies of the world. Version: 8th December 2006. http://delta-intkey.com’.