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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Cerodontha pygmaea (Meigen, 1830)
[Diptera: Agromyzidae]

Agromyza pygmaea Meigen, 1830. Syst. Beschr. 6: 183
Dizygomyza (Poemyza) verrucosa Hendel, 1931. Fliegen palaearkt. Reg. 6(2): 61
Phytobia (Poemyza) lapplandica Rydén, 1956. Opusc. ent. 21: 195
Cerodontha (Poemyza) pygmaea (Meigen, 1830); Nowakowski, 1962. Annls zool., Warsz. 20: 112
Dizygomyza (Poemyza) verrucosa Hendel, 1831; Nowakowski, 1967. Polskie Pismo ent. 37: 651
Cerodontha (Poemyza) pygmaea (Meigen, 1830); Nowakowski, 1967. Polskie Pismo ent. 37: 651
Cerodontha (Poemyza) pygmaea (Meigen, 1830); Nowakowski, 1972. Polskie Pismo ent. 42(4): 747
Cerodontha (Poemyza) pygmaea (Meigen, 1830); Spencer, 1972b. Handbk ident. Br. Ins. 10(5g): 104. Cerodontha (Poemyza) pygmaea (Meigen, 1830); Spencer, 1976. Fauna ent. Scand. 5(1): 198-9, fig. 348
Cerodontha (Poemyza) pygmaea (Meigen, 1830); Spencer, 1990. Host specialization in the world Agromyzidae (Diptera) : 354, 355, 356, 369, 370 (fig. 1386).


Leaf-mine: Normally several larvae feed together. Pupation in the mine (Spencer, 1976: 198).

Broad elongated blotch. Frass greenish. Larvae generally communal. Pupation within the mine. The black puaria are individially anchored within the mine with a silken thread attached at their rear end. Distinguishable from C. incisa only by means of the larva (Bladmineerders van Europa).

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.

Nowakowski (1973) gives details of the larva. Posterior spiracles each with 3 bulbs (Spencer, 1976: 198).

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).

Shining black (Spencer, 1976: 198), larvae individially anchored within the mine with a silken thread attached at their rear end (Bladmineerders van Europa).

Comments: The larvae of C. incisa and C. pygmaea are easily discriminated. The opposite holds for their pupariria, which is unfortunate because they are found frequently (much more often then the larvae) and because they are quite conspicuous. They are deep black with a strong violet or blue metallic shine; they are lying in the mine, not in pupariuml chamber, but anchored to the inner wall of the mine by means of a thread. Often several pupariria are found together, and then frequently the anchor wires are fused near the point where they are attached to the plan (Bladmineerders van Europa).

De Meijere (1928) and Hering (1957a) state that the distal margin of the common base of the rear pupariria is straight or convex in incisa, concave in pygmaea. This must be related to the size of the warts at either side of the rear spiracula, small in incisa, large in pygmaea. In practice, however, I find this character difficult to use. A second character invoked by them is that the intersegmental constrictions in incisa are roughened by tiny scalelike irregularities, while those in pygmaea have minute transverse corrugations. I have the impression that this is not reliable (Bladmineerders van Europa).

Cerodontha incisa or Cerodontha pygmaea puparium
Cerodontha incisa or Cerodontha pygmaea puparium
Image: © Willem Ellis (Bladmineerders van Europa)

Comments: Festuca gigantea is treated as Schedonorus gigantea (Giant Fescue) by Stace (2010).

Hosts in Great Britain & Ireland:

Poaceae        
Arrhenatherum       Robbins, 1991: 140
Arrhenatherum elatius False Oat-grass British Wild Flowers by John Somerville et al. Mines in BMNH
Arrhenatherum elatius False Oat-grass British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Brachypodium       Robbins, 1991: 137
Brachypodium sylvaticum False Brome British Wild Flowers by John Somerville et al. Mines in BMNH
Brachypodium sylvaticum False Brome British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Brachypodium sylvaticum False Brome British Wild Flowers by John Somerville et al. Spencer, 1972b: 122
Bromopsis ramosa Hairy-brome British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Bromus       Mines in BMNH
Bromus       Robbins, 1991: 137
Bromus       Spencer, 1972b: 123
Calamagrostis       Pitkin & Plant
Dactylis glomerata Cock's-foot British Wild Flowers by John Somerville et al. Spencer, 1972b: 123
Deschampsia       Robbins, 1991: 137
Deschampsia       Spencer, 1972b: 104
Deschampsia cespitosa Tufted Hair-grass British Wild Flowers by John Somerville et al. Mines in BMNH
Deschampsia cespitosa Tufted Hair-grass British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Deschampsia cespitosa Tufted Hair-grass British Wild Flowers by John Somerville et al. Spencer, 1972b: 123
Elymus       Robbins, 1991: 137
Elymus repens Common couch British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Festuca       Spencer, 1972b: 104
Festuca ovina Sheep's Fescue British Wild Flowers by John Somerville et al. Robbins, 1989: 21
Holcus       Robbins, 1983: 23
Lolium perenne Perennial Rye-grass British Wild Flowers by John Somerville et al. Mines in BMNH
Molinia caerulea Purple Moor-grass British Wild Flowers by John Somerville et al. Spencer, 1972b: 124
Phalaris       Robbins, 1991: 137
Phalaris arundinacea Reed Canary-grass British Wild Flowers by John Somerville et al. Robbins, 1989: 21

Hosts elsewhere:

Poaceae        
Agrostis       Spencer, 1976: 198
Agrostis       Spencer, 1990: 354
Agrostis stolonifera Creeping Bent British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Agrostis tenuis Common Bent   Bladmineerders van Europa
Ammophila       Spencer, 1990: 354
Ammophila arenaria Marram   Bladmineerders van Europa
Apera       Spencer, 1990: 354
Apera spica-venti Loose Silky-bent   Bladmineerders van Europa
Arrhenatherum       Spencer, 1990: 354
Arrhenatherum elatius False Oat-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Avena       Spencer, 1990: 354
Avena sativa Oat   Bladmineerders van Europa
Avenula       Bladmineerders van Europa
Brachypodium       Spencer, 1990: 355
Brachypodium pinnatum Heath False-brome   Bladmineerders van Europa
Brachypodium sylvaticum False Brome British Wild Flowers by John Somerville et al. Spencer, 1976: 198
Brachypodium sylvaticum False Brome British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Bromus       Spencer, 1990: 354
Bromus tectorum Drooping Brome   Bladmineerders van Europa
Calamagrostis canescens Purple Small-reed   Bladmineerders van Europa
Calamagrostis epigejos Wood Small-reed British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Calammophila baltica Purple Marram   Bladmineerders van Europa
Dactylis       Spencer, 1990: 355
Dactylis glomerata Cock's-foot British Wild Flowers by John Somerville et al. Spencer, 1976: 198
Dactylis glomerata Cock's-foot British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Dactylis polygama Slender Cock's-foot   Bladmineerders van Europa
Deschampsia       Spencer, 1990: 354
Deschampsia cespitosa Tufted Hair-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Elymus caninus Bearded Couch British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Elymus repens Common Couch British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Elytrigia       Spencer, 1990: 356
Elytrigia       Spencer, 1976: 198
Elytrigia       Bladmineerders van Europa
Festuca       Spencer, 1976: 198
Festuca       Spencer, 1990: 355
Festuca altissima Wood Fescue British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Festuca gigantea Giant Fescue British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Glyceria       Bladmineerders van Europa
Glyceria       Spencer, 1990: 354
Holcus       Spencer, 1976: 198
Holcus       Spencer, 1990: 354
Holcus lanatus Yorkshire-fog British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Hordeum vulgare Six-rowed Barley   Bladmineerders van Europa
Lolium       Spencer, 1990: 355
Lolium perenne Perennial Rye-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Melica nutans Mountain Melick British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Molinia caerulea Purple Moor-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Phalaris       Bladmineerders van Europa
Phleum       Spencer, 1976: 198
Phleum       Spencer, 1990: 355
Phleum pratense Timothy British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Phragmites australis Common Reed British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Poa       Spencer, 1976: 198
Poa       Spencer, 1990: 355
Poa compressa Flattened Meadow-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Poa pratensis Smooth Meadow-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Poa trivialis Rough Meadow-grass British Wild Flowers by John Somerville et al. Bladmineerders van Europa
Secale cereale Rye   Bladmineerders van Europa
Triticum aestivum Bread Wheat   Bladmineerders van Europa

Time of year - mines: (May) June-September (October) (Bladmineerders van Europa).

Time of year - adults: June-August.

Distribution in Great Britain & Ireland: Widespread and common in Britain including Dunbarton (Bonhill) (Spencer, 1972b: 104), Warwickshire (Coventry, Holbrooks) (Robbins, 1991: 137); Cambridgeshire, East Gloucestershire, Huntingdonshire, North Hampshire, Northamptonshire, North-west Yorkshire, Nottinghamshire, South Somerset, South-west Yorkshire, Surrey and Westmorland (NBN Atlas).

Also recorded in the Republic of Ireland: Co. Clare (Spencer, 1972b: 104)

Distribution elsewhere: Widespread and frequently common in much of Europe including Denmark, Sweden, Finland (Spencer, 1976: 198), The Netherlands (Bladmineerders van Europa), Belgium (Scheirs and de Bruyn, 1992), Germany (Spencer, 1976: 554), Austria, Canary Is., Czech Republic, Estonia, French mainland, Hungary, Italian mainland, Latvia, Lithuania, Madeira, Poland, Slovakia, Spanish mainland and Yugoslavia (Martinez in Fauna Europaea).

Also recorded in Alaska and Canada (Spencer, 1976: 198).

NBN Atlas links to known host species:

Agrostis capillaris, Agrostis stolonifera, Agrostis tenuis, Ammophila arenaria, Apera spica-venti, Arrhenatherum elatius, Avena sativa, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis ramosa, Bromus tectorum, Calamagrostis baltica, Calamagrostis canescens, Calamagrostis epigejos, Calammophila baltica, Dactylis glomerata, Deschampsia cespitosa, Elymus caninus, Elymus repens, Festuca altissima, Festuca gigantea (= Schedonorus gigantea), Festuca ovina, Holcus lanatus, Hordeum vulgare, Lolium perenne, Melica nutans, Molinia caerulea, Phalaris arundinacea, Phleum pratense, Poa compressa, Poa pratensis, Poa trivialis, Secale cereale, Triticum aestivum

British and Irish Parasitoids in Britain and elsewhere:

Chalcidoidea   
Chrysocharis gemma (Walker, 1839) Eulophidae: Entedoninae
Chrysocharis idyia (Walker, 1839) Eulophidae: Entedoninae
Chrysocharis polyzo (Walker, 1839) Eulophidae: Entedoninae
Hemiptarsenus unguicellus (Zetterstedt, 1838) Eulophidae: Eulophinae
Merismus megapterus Walker, 1833 Pteromalidae: Miscogastrinae
Ichneumonoidea  
Chorebus asramenes (Nixon, 1945) Braconidae: Alysiinae
Chorebus cytherea (Nixon, 1937) Braconidae: Alysiinae
Chorebus difficilis Griffiths, 1968 Braconidae: Alysiinae
Chorebus poemyzae Griffiths, 1968 Braconidae: Alysiinae
Chorebus talaris (Haliday, 1839) Braconidae: Alysiinae
Dacnusa adducta (Haliday, 1839) Braconidae: Alysiinae
Dacnusa maculipes Thomson, 1895 Braconidae: Alysiinae
Dapsilarthra sylvia (Haliday, 1839) Braconidae: Alysiinae
Exotela flavicoxa (Thomson, 1895) Braconidae: Alysiinae
Heterolexis balteata (Thomson, 1895) Braconidae: Alysiinae
Apodesmia posticatae (Fischer, 1957) Braconidae: Opiinae
Atormus victus (Haliday, 1837) Braconidae: Opiinae
Eurytenes abnormis (Wesmael, 1835) Braconidae: Opiinae
Opius singularis Wesmael, 1835 Braconidae: Opiinae
Phaedrotoma rex (Fischer, 1958) Braconidae: Opiinae
Phaedrotoma variegata (Szépligeti, 1896) 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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