Pest Fruit Flies of the World – Larvae
Trypeta pomonella Walsh
Apple maggot, Apple maggot fly. Body length 8–11mm (?); elongate-cylindrical (?). Integument unsclerotized, entirely whitish to yellowish. Caudal ridge absent. Mature larvae unable to jump.
Head. Head of normal shape; cephalic lobes slightly developed. Antenna 2-segmented. Stomal organ: primary lobe rounded, protuberant; number of peg sensilla one (small); peg sensilla unbranched; other peg-sensilla-like structures absent. Stomal region: secondary lobes absent; sclerotized stomal guards present; number of sclerotized stomal guards 2 (large). Oral ridges present; number of oral ridges 5–7 (short); margins entire. Accessory plates absent. Elongate, finger-like lobes arising above mandibles absent. Median oral lobe absent or not protruding. Labium broad.
Cephalopharyngeal skeleton. Mandibles: subapical teeth absent (also~Phillips'specimens); base stout, nearly perpendicular to a line from ventral part of base to apex of mandible. Parastomal bars elongate, free from hypopharyngeal sclerite. Dental sclerites apparently absent, not visible in lateral view.
Spinules and creeping welts. Dorsal spinules on segments with an unusual distribution (T2-A8).
Caudal segment (a8) and anal lobes. Sensilla on caudal segment 10 pairs, with at least 7 pairs visible under dissecting microscope. Intermediate caudal sensillum I2 obvious (?). Intermediate caudal sensilla I1a&b and I2 on a single tubercle (?). Ventral caudal sensilla obvious, on a papilla or tubercle. Anal lobes very protuberant, or plainly visible, but not strongly protuberant; simple.
Anterior spiracles. Anterior spiracle elevated, margin convex to straight. Anterior spiracular tubules 17–25 (19–22~Phillips 1946); in two rows (irregular).
Posterior spiracles. Posterior spiracular area not distinctly set off from caudal segment. Posterior spiracles: slits 3.5–4.5x longer than wide (range estimated, LEC coded about 4). Dorsal spiracular processes with numerous trunks arising from a short or semicircular base, or with a few trunks radiating from a short or semicircular base (medium processes). Number of dorsal spiracular processes 9–16 (~WEH;11–15~Phillips). Number of ventral spiracular processes 9–16 (~WEH;11–15~Phillips). Number of lateral spiracular processes 6–10 (~WEH;9~Phillips). Area between posterior spiracles smooth.
Host plants. Rosaceae (Crataegus; Amelanchier, Aronia, Cotoneaster, Malus, Prunus, Pyracantha, Pyrus, Sorbus).
Ericaceae, Pickett 1937, Pickett & Neary 1940 (prob. misid. of R. mendax and other spp., White & Elson-Harris 1992).
Part of plant attacked: fruit.
Biogeographic region. Nearctic, Neotropical.
Specimens examined. Based on description by White and Elson-Harris (1992; Vermont: ex Malus domestica).
Sources of data and SEM numbers: 376SEM.
Illustrations. • Cephalopharyngeal skeleton, spiracles. • Caudal segment (posterior & lateral). • Cephalopharyngeal skeleton (lateral). • Cephalopharyngeal skeleton, spiracles. • Head (anteroventral) SEM. • Stomal organ SEM. • Head (lateral) SEM. • Anterior spiracle SEM. • Caudal segment (posterolateral) SEM. • Posterior spiracles SEM. • Caudal segment (lateral) SEM. • Anal lobes SEM.
Cite this publication as: ‘L.E. Carroll, A.L. Norrbom, M.J. Dallwitz, and F.C. Thompson. 2004 onwards. Pest fruit flies of the world – larvae. Version: 8th December 2006. http://delta-intkey.com’.