Nysson trimaculatus (Rossi,1790)

Synonyms

Nysson nigripes Spinola, 1808; Nysson geniculatus Olivier, 1812

Description and notes

A species of Nysson that apparently has two hosts in this country and is sometimes easier to locate than its hosts.

Distribution

Recorded widely in the southern half of England, from Cornwall to Kent and north to Warwickshire and Yorkshire; also the Channel Islands. Abroad, rare but widely distributed in Europe; also Japan (Lomholdt, 1975-1976), and recently reported from China.

Status (in Britain only)

Listed as Notable B by Falk (1991) [now known as Nationally Scarce (Nb)], and clearly scarcer than its hosts in most parts of the country, though it has been noted as relatively frequent in Kent, where it is sometimes easier to find than its host there, Gorytes bicinctus. It may have expanded its range northwards in recent decades and is now known from several Yorkshire sites, a county from which it was unrecorded prior to the 1970s.

Habitat

Recorded from a variety of open habitats on light soils, including heathland, dry grassland and scrub, open woodland, coastal landslips and soft rock cliffs, quarries and other post-industrial sites and occasionally heavily urbanised locations. Three specimens were even obtained from a roadside hedge in central London (K M Guichard, pers. obs.). Usually observed running on sparsely-vegetated ground or low herbage.

Flight period

Early June to early September.

Flowers visited

Specimens have occasionally been observed running over sycamore (Acer pseudoplatanus) leaves, presumably attracted by honeydew (G R Else, pers. comm.). In France, Bitsch et al. (1997) mention the inflorescences of Apiaceae.

Parasites

No information available.

Parasitic biology

N. trimaculatus is a cleptoparasite of Gorytes quadrifasciatus and G. bicinctus, relying entirely on the former species in the north of its range (e.g. Warwickshire and Yorkshire), and largely on G. bicinctus in Kent, where G. quadrifasciatus is scarce. In Fennoscandia, Lomholdt additionally lists G. laticinctus, a rare species in Britain but occurring within the range of N. trimaculatus.

Author of profile

S J Falk.

Year profile last updated

Proofed: March 2012