nigrescens Hendel, 1920. Arch. Nautrgesch. 84A(7)(1918):
Agromyza heringi de Meijere, 1925. Tijdschr. Ent.
Agromyza nigrescens Hendel, 1920; Hendel, 1931. Fliegen
palaearkt. Reg. 6(2): 134
Agromyza nigrescens Hendel, 1920; Spencer, 1972b. Handbk
ident. Br. Ins. 10(5g): 41, 116
Agromyza nigrescens Hendel, 1920; Spencer, 1976. Fauna
ent. Scand. 5(1): 127-8, figs 114, 219-221.
Agromyza nigrescens Hendel, 1920; Spencer, 1990. Host
specialization in the world Agromyzidae (Diptera) : 151 (figs
568-9), 152, 157, 178, 398.
initially narrow linear mine which after the first moult widens
into large linear or irregular blotch; frass in distinct rows in
the early linear section, later more scattered (Spencer,
1976: 128-9, fig. 221).
mine is described by Hering (1957a) as follows: Upper-surface mine.
The start is corridor-like and generally follows the leaf margin.
Further on the mine widens considerably, forms a secondary blotch
and gets irregular sides that are deeply eaten out. Primary and
secondary feeding lines clearly visible. Frass mostly in large clumps.
Pupation outside the mine. The mine only rarely occurs in Geranium
robertianum; the frass then is fine-grained and the mines are
smaller. Hering didn't think it impossible the the miners of Geranium
robertianum and the other Geranium species might be a
different species. Dutch material might form a different third species
(Bladmineerders van Europa).
The first instar larva makes an initial corridor, with frass in two lines. Then a large irregular blotch is formed (British
Larva: The larvae of flies are leg-less maggots without a head capsule (see examples). They never have thoracic or abdominal legs. They do not have chewing mouthparts, although they do have a characteristic cephalo-pharyngeal skeleton (see examples), usually visible internally through the body wall.
The larva is illustrated in Bladmineerders van Europa.
Puparium: The puparia of flies are formed within the hardened last larval skin or puparium and as a result sheaths enclosing head appendages, wings and legs are not visible externally (see examples).
Reddish-brown; posterior spiracles each with 3 bulbs (Spencer,
1976: 128). The puparium is illustrated in Bladmineerders van Europa.
Hosts in Great Britain & Ireland:
of year - mines: September.
of year - adults: Currently unknown.
in Great Britain & Ireland: Widespread in Britain including
Middlesex (Greenford) (British
leafminers), Surrey (Kew), Yorkshire (Gorsdale Scar), Cardiff,
Edinburgh (Spencer, 1972b:
41), Warwickshire (The Bogs) (Robbins,
1991: 38) and Cambridgeshire (VC29), Cardiganshire (VC46), East Norfolk (VC27), East Suffolk (VC25), Glamorganshire (VC41), North Somerset (VC6), West Kent (VC16), West Norfolk (VC28), West Suffolk (VC26) and Westmorland (NBN
elsewhere: Widespread in continental Europe including Denmark,
Finland, Norway, Sweden, the Mediterranean area (Spencer,
1976: 128), Germany (Spencer,
1976: 546), Canary Is., Czech Republic, Estonia, Italian mainland,
Lithuania, Malta, Poland, Spanish mainland and Switzerland (Martinez
in Fauna Europaea).
NBN Atlas links to known host species: