The leaf and stem mines of British flies and other insects
 

(Coleoptera, Diptera, Hymenoptera and Lepidoptera)

by Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds

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Agromyza nigrescens Hendel, 1920
[Diptera: Agromyzidae]

Geranium leaf-miner


Agromyza nigrescens Hendel, 1920. Arch. Nautrgesch. 84A(7)(1918): 117
Agromyza heringi de Meijere, 1925. Tijdschr. Ent. 68: 220
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.


Leaf-mine: An 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).

The 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 leafminers).

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.

Agromyza nigrescens puparium
Agromyza nigrescens puparium
Image: © Willem Ellis (Bladmineerders van Europa)

Hosts in Great Britain & Ireland:

Geraniaceae        
Geranium       Mines in BMNH
Geranium       British leafminers
Geranium       Spencer, 1972b: 116
Geranium robertianum Herb-Robert British Wild Flowers by John Somerville et al. Robbins, 1991: 38

Hosts elsewhere:

Geraniaceae        
Erodium moschatum Musk Stork's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium       Spencer, 1976: 128
Geranium       Spencer, 1990: 157
Geranium columbinum Long-stalked Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium molle Dove's-foot Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium nodosum Knotted Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium palustre     Bladmineerders van Europa
Geranium phaeum Dusky Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium pratense Meadow Crane's-bill British Wild Flowers by John Somerville et al. Spencer, 1990: 152
Geranium pratense Meadow Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium purpureum Little-Robin   Bladmineerders van Europa
Geranium pusillum Small-flowered Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium robertianum Herb-Robert British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium rotundifolium Round-leaved Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium sanguineum Bloody Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Geranium sylvaticum Wood Crane's-bill British Wild Flowers by John Somerville et al. Bladmineerders van Europa

Time of year - mines: September.

Time of year - adults: Currently unknown.

Distribution 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, Cardiganshire, East Suffolk, Easterness, Glamorgan, North Somerset and Westmorland (NBN Atlas).

Distribution 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:

Geranium columbinum, Geranium molle, Geranium nodosum, Geranium phaeum, Geranium pratense, Geranium purpureum, Geranium pusillum, Geranium robertianum, Geranium rotundifolium, Geranium sanguineum, Geranium sylvaticum, Erodium moschatum

Parasitoids:

Chalcidoidea  
Chrysocharis amyite (Walker, 1839) Eulophidae: Entedoninae
Miscogaster hortensis Walker, 1833 Pteromalidae: Miscogastrinae
Ichneumonoidea  
Chorebus credne (Nixon, 1944) Braconidae: Alysiinae
Apodesmia posticatae (Fischer, 1957) Braconidae: Opiinae
Opius ambiguus Wesmael, 1835 Braconidae: Opiinae
Opius pallipes Wesmael, 1835 Braconidae: Opiinae
Phaedrotoma reptantis (Fischer, 1957) Braconidae: Opiinae


External links: Search the internet:
Biodiversity Heritage Library
Bladmineerders van Europa
British leafminers
Encyclopedia of Life
Fauna Europaea
NBN Atlas
NHM UK Checklist
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