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Eristalis cryptarum

 
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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: Eristalis cryptarum Reply with quote

Eristalis cryptarum (Fabricius, 1794)

Identification ease/difficulty: 2

StatusSources of information
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Last edited by stuart on Wed Jun 01, 2005 9:39 pm; edited 1 time in total
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stuart
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Joined: 11 May 2005
Posts: 737
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.

Eristalis cryptarum (Fabricius, 1794) Eoseristalis cryptarum (Fabricius, 1794) in Levy & Levy (1994)

Biology: The larvae remain unknown, but are likely to be of the ‘long-tailed’, aquatic type. Appears to be associated with sheltered and somewhat acid pools supporting plants such as Sphagnum, Menyanthes, Narthecium and Caltha. Adults can be found visiting flowers nearby including Ranunculus, Caltha, Menyanthes and Cardamine. Has a very log flight period, so presumed to be multi-brooded

Distribution: A south-western species with many old records from Dartmoor and the New Forest, mostly dating from the last century up to about 1950; also from Dorset, especially Studland, in the 1930s, and Cornwall in 1910. Records became increasingly scarce through the 1960s, and there is only a single record from the early 1970s, from Dartmoor. Two Dipterists’ summer field meetings in Devon in the late 1970s and 1980s failed to find it and the species was feared extinct. Then in 1993 it was re-discovered at one of its old localities on Dartmoor and it has subsequently been found at seven localities in the immediate vicinity
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stuart
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Location: Peterborough, UK

PostPosted: Sun May 29, 2005 9:08 am    Post subject: Data sheet from Insect Red Data Book, Shirt, 1987 Reply with quote

Datasheet from the Insect Red Data Book, Shirt (1989).

Eristalis (Eoseristalis) cryptarum (F., 1794) VULNERABLE

Identification: Stubbs & Falk (1983), pp. 97 and 194, pl. 11:8.

Distribution: South-west England to the New Forest and Gloucestershire.

Habitat and ecology: The larvae are of the rat-tailed maggot type adapted to aquatic conditions. Little is known of the ecology but it is belived that there may be a preference for stream sides and pond margins with a rich marsh soil and plants such as yellow flag Iris pseudacorus.

Status: Records are sparse and mostly old. Brown & Searle (1974) in a survey of east Dorset cited 1938 as the last known record. Recent surveys in the New Forest have not revealed the species. There has been recording effort in south-west England in recent years which, though not exhaustive, has only revealed a single specimen, in Devon.

Author: A.E. Stubbs.
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stuart
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PostPosted: Sun May 29, 2005 9:08 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).

ERISTALIS CRYPTARUM (Fabricius) VULNERABLE

DISTRIBUTION South-west England (Cornwall, Devon, Somerset, Dorset, Hampshire). Most records are from the New Forest and Dartmoor.

HABITAT Lush marshy spots, stream sides and pond margins with a rich boggy soil and such plants as Iris.

ECOLOGY Larvae aquatic, probably amongst the submerged parts of marginal vegetation and are of the rat tailed maggot type. Adults recorded from March to September.

STATUS Heavily declined with only two known post 1960 sites within the Dartmoor area (Dartmeet 1978 and Soussons Plantation 1966) and it has always been rather sporadic in its occurence. It may be extinct in other parts of its range or overlooked among commoner Eristalis species.

THREAT Drainage of marshes, with a resultant loss of ponds, canalisation of rivers and ditching of streams with a loss of the marginal vegetation in which the larvae probably develop. Also excessive trampling of river banks at sites such as Dartmeet, Devon and pollution such as agricultural run-off.

MANAGEMENT Maintain a high stable water level in marshes, ensure a rich marginal vegetation around water bodies.
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