ERISTALIS Rum, E

312. 314. figure 312. Eristalinus sepulcralis, habitus of female. figure 314. Eristalinus aeneus, head of male figure 313. Eristalinus aeneus, habitus of (Verlinden). female (Verlinden). ERISTALIS rum, E. abusiva and E. nemorum; secondly E. horticola and E. jugorum and thirdly Eristalis picea, E. rupium, E. pseudorupium, Introduction E. alpina and E. nemorum. The key is based on Kanervo (1938), Eristalis can be found everywhere and Nielsen (1995), Bartsch (1997), Zeegers many are common garden visitors. A lim- and Van Veen (1992), Van Veen and ited number have quite specific habitat Zeegers (1996), and Hippa et al. (2001). preferences and restricted distributions, Nielsen (1995) clarifies the status of for example E. cryptarum, which occurs in E. fratercula, E. vallei and E. gomojunovae. bogs. The larvae of Eristalis are detri- Hippa et al. (2001) clarify the status of tivorus and bacteria-eating filter feeders, E. rupium, E. picea and E. pseudorupium. living in aquatic or semi-aquatic condi- The International Commission on tions, including liquified faeces. Larvae of Zoological Nomenclature restored the E. tenax have incidentally been reported name E. horticola (formerly E. lineata) and to occur in the intestinal tract, causing E. nemorum (formerly E. interrupta). human myasis (maggot infestation). Key Recognition 1.a. Arista bare or hairs shorter than twice Most Eristalis can be identified by species the diameter of arista base (figure 315) › specific characteristics, for example, E. 2 tenax by its hair bands on the eyes and E. 1.b. Arista feathery, hairs much longer similis (= E. pratorum) by its long pale than twice the diameter of arista (figure pterostigm. The colouration and extent of 316) › 8 the yellow markings on the abdomen vary with temperature (Holloway, 1993). 2.a. Eyes without bands of hair › 3 In particular, E. arbustorum and E. horticola 2.b. Eyes with 2 distinct bands of hair extend the amount of yellow on the (figure 317); arista bare. 14-16 mm. abdomen as the season progresses, more Cosmopolitan › Eristalis tenax noticeably for males than for females. A Linnaeus number of species are easily confused Jizz: stout species with completely shiny abdomen. (particularly in the field): firstly E. arbusto- Femur 3 thick, hangs down while hovering. 100 long hairs almost bare figure 315. Eristalis tenax, antenna figure 316. Eristalis arbustorum, antenna (Verlinden). (Verlinden). orange figure 318. Eristalis cryptarum, leg 1 figure 317. Eristalis tenax, head (Verlinden). (Verlinden). separated 4.b Tars 3 orange; scutellum whitish; back of thorax and tergite 2 with white hairs, tergite 3 with black hairs, tergite 4 with red hairs. 12-15 mm. Northern Europe, south just into Central Europe (Baltic Sea) › Eristalis oestracea Linnaeus Jizz: remarkably like Eriozona syrphoides. figure 319. Eristalis abusiva, head of male 5.a. Face with a broad, bare, black stripe; (Verlinden). tibia blackish: black on top 1/2 or more; males: eyes meeting › 6 Jizz: scutellum pale, contrasts with abdomen. 5.b. Face without or (in older specimens) 3.a. Tibia: at least tibia 3 dark at tip, often with a narrow black stripe; tibia pale: other tibia also dark at tip; antennae: 3rd blackish on top 1/4 or less. Males: eyes segment black to brownish › 4 separate (figure 319). 11-13 mm. › 3.b. Tibia 1-3 entirely orange (figure Eristalis abusiva Collin 318); antennae: 3rd segment reddish. 10- Jizz: scutellum shiny, not contrasting much with 12 mm. Northern and Central Europe, the thoracic dorsum. Tibia 2 very pale, often with in Asia east to Mongolia › Eristalis only a blackish patch at the very end, in contrast cryptarum Fabricius to E. arbustorum. Jizz: whitish hind margins of tergites and orange legs, wings infuscate at front. 6.a. Face: below eyes pale-haired, in front view ground colour black or with yel- 4.a. Tars 3 black; scutellum yellow (only lowish parts; tergite 2: yellow spots (or whitish in E. anthophorina); tergites: hair place where they are normally present) colours not in white-black-red pattern, dull or semi-shiny (compare with shiny tergite 4 with white, brown or reddish parts of tergite 3, take care in strong hairs › 5 light) › 7 101.

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