Callicera spinolae

[stuart]

Callicera spinolae Rondani, 1844

Identification ease/difficulty: 2

Status

• Endangered in Falk (1991)
• Endangered in Shirt (1987)
• BAP priority in UK BAP (1995)

Habitat indicator status

• H3 in Stubbs (1982)
• Listed as a saproxylic indicator in Speight (1989)

Sources of information

• Page 159, Pl. 9. fig 3 in Stubbs & Falk (1983)
• Map here and page 23 in Ball & Morris (2000)
• Page 239, Pl. 9, fig. 1 in Stubbs & Falk (2002)

Pictures:

[stuart]

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

Callicera spinolae Rondani, 1944

Biology: The larvae inhabit water-filled rot holes in large, old *, and have also been reared from Populus in continental Europe. Adults are seldom found, but several records refer to individuals feeding on Hedera flowers in the autumn

Distribution: This extremely rare species has always been confined to East Anglia, and there are recent records only from two Cambridgeshire sites. It was extinct at one of these by 1983 and, at the other, was reduced to breeding in two trees, one of which blew down in the winter of 1994/95. English Nature has commissioned a survey of all historic localities, and other potential sites in East Anglia, under the Biodiversity Action Plan. No specimens were found in the ??? sites visited in 1997, but the most promising sites were revisited in 1998 and a single adult was found in ?Norfolk?

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

Callicera spinolae Rondani, 1844 ENDANGERED

Identification: Stubbs & Falk (1983), pp. 73 and 159, pl. 9:1.

Distribution: A few localities in East Anglia. For map see Entwistle & Stubbs (1983), map 3.

Habitat and ecology: Adults occur at ivy blossom Hedera helixin the autumn. The larvae are unknown, but almost certainly live in rot-holes in trees.

Status: Always a rarity but was reasonably strong at one site in the 1970s. However, it has rapidly declined and has seemingly disappeared in the last few years. There is strong reason to believe that it bred in elm trees (Ulmus species) which have now died and been removed after Dutch elm disease. It was rediscovered at its former strongest site in 1984, but is scarce, apparently dependent now on beech*.

Author: A. E. Stubbs, using additional information from I. Perry (pers. comm.).

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

CALLICERA SPINOLAE (Rondani) ENDANGERED

DISTRIBUTION Recorded from some seven sites in East Anglia: Southwold (1928), Bradiston Marshes (1942), Monks Soham (1947) and Iken (late 1940s) all in Suffolk; Houghton, Norfolk (1972, 1974); Gog Magog Hills (1979, 1984) and Lode (1971, 1972, 1974, 1975, 1978), Cambridgeshire.

HABITAT Almost certainly associated with very old broadleaved trees, with adults usually occurring near woods or in parkland/garden situations.

ECOLOGY In Russia, this species has been reared from rot holes in poplars (G. Rotheray - pers. comm.). Adults are usually found at the flowers of ivy on walls in late September and October.

STATUS Rather unclear due to the highly sporadic nature of the records. The data from Lode and the Gog Magog Hills suggests that the species does breed in Britain as opposed to being a migrant, and the fluctuations in the adult population may be related to changes in the amount of the resource for larval development. It should be noted that the great storm of 1987 has destroyed most of the old trees at two of the known sites, placing the fly into an even more precarious position.

THREAT Removal of post-mature trees and lack of regeneration of suitable trees through changes in woodland management.

MANAGEMENT Retain any old broadleaved trees, especially those with obvious rot holes, and ensure a continuity of suitable trees in the future; also ivy-clad walls for adult feeding.