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Didea intermedia

 
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stuart
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Joined: 11 May 2005
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Location: Peterborough, UK

PostPosted: Sat May 28, 2005 5:39 pm    Post subject: Didea intermedia Reply with quote

Didea intermedia Loew, 1854

Identification ease/difficulty: 4

StatusSources of information
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stuart
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Joined: 11 May 2005
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Location: Peterborough, UK

PostPosted: Sun May 29, 2005 8:41 am    Post subject: Species account from the Provisional atlas Reply with quote

Species account from Provisional atlas of British hoverflies, Ball & Morris, 2000.

Didea intermedia Loew, 1854

Biology: Larvae are strongly associated with Pinus and have been found feeding on aphids on Pinus nigra. Adults are almost always associated with coniferous forest, including conifers planted on sand dunes. A few records from deciduous woodland in southern Britain are suspect, and may well be misidentifications of D. fasciata

Distribution: A northern species, with most records from Scotland and north-west England. It occurs on coniferised heathland on the Surrey/Hampshire border, and according to Coe (1953) there are old but reliable records from the New Forest
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stuart
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Location: Peterborough, UK

PostPosted: Sun May 29, 2005 9:09 am    Post subject: Data sheet from National Review of Diptera, Falk, 1991 Reply with quote

Datasheet from the Review of Scarce and Threatened Diptera, Falk (1991).

DIDEA INTERMEDIA Loew NOTABLE

DISTRIBUTION Records scattered widely in England and Scotland. Most frequent in Scotland but also with numerous records for Windsor Forest and the New Forest. The lack of records from Wales is interesting as much apparently suitable habitat is available there.

HABITAT Most records from coniferous woodland, especially plantations and adjacent areas and with a few records from Caledonian pine forest and it may require younger pine trees or denser stands. In southern England there seems to be some association with heathland, quite independant of conifers, although it can occur in plantations here.

ECOLOGY Larvae aphidophagous and have been found abroad on pine feeding on Schizolachnus pineti. Adults have also been observed taking great interest in gorse infested with an Aphis species in the New Forest. Adults recorded from May to September, probably as two broods and may be found on the flowers of umbels and bedstraw.

STATUS A very local but not infrequent species in afforested areas of the Scottish Highlands. It seems to be increasing here, with populations enhanced through coniferisation. In southern England there seems to be a definite decline probably through loss of heathland, though there is evidence to suggest that conifer plantations are being colonised, though whether this is by the original southern heathland populations is indeterminable. It seems likely that the species was indigenous to Caledonian forests prior to coniferisation of highland areas.

THREAT None in Scotland as conifer plantations are not a threatened resource. Loss of heathland in the south (where gorse may provide the larval habitat) to agriculture, intensive forestry, accidental fires and scrub invasion through mis-management.

MANAGEMENT Retain heathland sites in the south and maintain gorse by employing traditional management. Management probably unnecessary in Scotland other than retaining open rides and clearings in plantations with plenty of flowers for adult feeding, and encouraging pine regeneration in Caledonian forests by protecting saplings from grazing by deer.
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