Centaurea knapweed, cornflower

Dichotomous table for leafminers

Incl. Cnicus, Colymbada, Cyanus, Jacea, Mantisalca.

1a fleck mine => 2

1b no fleck mine => 10

1c galls, etc => Tables for all parasites per species

2a opening in the mine comparatively small, in the centre of the mine, perfectly circular => 3

2b opening large, angular, often excentric, sometimes just a tear => 8

3a larva in a case composed of well recognisable leaf material => 4

3b case made out of silk => 5

4a spatulate leaf case: Coleophora brevipalpella

4b composite leaf case: Coleophora didymella

5a tubular silken case => 6

5b sheath case => 7

6a case (dark) brown: Coleophora paripennella

6b case straw coloured: Coleophora peribenanderdi

7a case with some oblique ribs: Coleophora caelebipennella

7b case with some transverse ribs behind the mouth: Coleophora rectilineella

7b case smooth, slender: Coleophora conspicuella

8a fleck mine small, opening angular; larva mines from a helicoidal case: Apterona helicoidella

8b mine large; opening a tear at the (lower) side of the mine => 9

9 Six Jordanita species form mines of this type. The colour of the larvae is too variable for a reliable identification, and morphological differences are not known to me: budensis, Jordanita chloros, globulariae, graeca, notata subsolana

10a mine centered on the midrib, or ending there => 11

10b mine independent of the midrib => 19

11a a narrow corridor that ends upon the midrib: Ophiomyia curvipalpis

11b mine starting from, or on top of, the midrib => 12

12a pinnately branching corridor, main axis over or in the midrib; larva a maggot => 13

12b mine not so; larva with chitinised head => 14

13a main axis of the mine on top of the midrib; frass as numerous strings in the mine: Liriomyza strigata

13b main axis within the midrib; hardly any frass visible, and then not as strings: Ophiomyia beckeri

14a larva without feet: Orthochaetes setiger

14b larva with thoracic feet and prolegs => 15

15a older larve living free among spun leaves: Cnephasia sedana

15b larvae mine all their life => 16

16a mine with clear length folds: Scrobipalpa perinii

16b mine flat => 17

17a overlying the midrib the mine forms a corridor, lined with silk and frass; from there lobes or branches enter the blade => 18

17b mine an elongate blotch on, and at either sides of, the midrib: Agonopterix carduella

18a the larvae regularly move to another leaf, making silken tubes all the while: Scrobipalpa halonella

18b the larva doesn’t move to new leaves: Scrobipalpa acuminatella

18c the biology of Scrobipalpa pauperella is poorly known, but probably resembles that of acuminatella

19a mine small, of indefinite shape => 20

19bclear, not unusually small, corridor or blotch mines => 22

20a larva: pinacula colourless (the bases of the setae themselves are black): Cnephasia incertana

20b pinacula black => 11

21a larva: behind/below the anus a chitinous comb: Cnephasia asseclana

21b anal comb absent: Cnephasia stephensiana

22a primary blotch => 23

22b corridor, rarely (through confluence) a secondary blotch => 28

23a the blotch is preceded by a corridor: Pegomya centaureae

23b no preceding corridor present => 24

24a mine strongly contracted by silk deposited inside: Cnephasia lineata

24b mine flat => 25

25a strong concentration of frass in the centre of the mine; there also pupation takes place, in a cocoon; larva with a chitinised head => 26

25b frass irregularly distributed; pupation within the mine, but not in a cocoon; larva a maggot: Phytomyza cinerea

26a oviposition in the midrib; from there the mine extends into the blade => 27

26b oviposition in the leaf margin: Pseudorchestes pratensis

26c Pseudorchestes cinereus and heringi are insufficiently known, possibly they are just synonyms

27a on Centaurea nigra: Pseudorchestes persimilis

27b on Centaurea scabiosa: Pseudorchestes ermischi

28a corridor short; older larva lives free => 29

28b corridor long of very long; the larva remains in the mine till (just before) pupation => 31

29a head yellowish to brown; pale yellow or green: Agonopterix arenella

29b head black; green => 30

30a dull green; June – early July: Agonopterix subpropinquella

30b apple green; July – early August: Agonopterix propinquella

31a larva with chitinised head, but without feet: Orthochaetes setiger

31b larva with chitinised head; thoracic feet present => 32

31c larva maggot: no feet, and seemingly no head either => 34

32a frass more or less in a central line: Sphaeroderma rubidum

32b frass mostly scattered => 33

33a part of of the mine follows the leaf margin: Sphaeroderma testaceum

33b corridor less closely following the leaf margin: Sphaeroderma rubidum

34a puparium in the mine => 35

34b pupation external => 37

35a little branching, yellowish green, interparenchymatous corridor: Phytomyza spinaciae

35b irregularly branching, upper-surface (whitish) corridor => 36

36a corridor sides rather straight; larva: rear spiraculum with 6-8 papillae: Chromatomyia cf. syngenesiae

36b corridor sides irregularly scalloped out; rear spiraculum with 12-18 papillae: Phytomyza autumnalis

37a frass in fine grains; larva: rear spiraculum with c. 17 papillae: Phytomyza spoliata

36b frass in strings and pearl chains; rear spiraculum with 8-9 papillae: Liriomyza centaureae

37a the larva mostly voids its intestine only after leaving the mine, rarely just before; rear spiraculum with c. 30 papillae: Aulagromyza similis

36b frass very variable; rear spiraculum with with c. 18 papillae; (only?) on Centaurea montana: Phytomyza montana

Not included in the key: Bucculatrix infans; Coleophora argenteonivea, centaureivora, gardesanella; Dibolia pelleti; Liriomyza bessarabica, bryoniae, trifolii; Phytomyza spinaciae; Scrobipalpa arenbergeri; Scrobipalpula psilella, seniorum.

Liriomyza centaureana Hering, 1936, included by Hering (1957a) in his key for Centaurea has been found to be synyonym of L. congesta; its spurious association with Centaurea was due to a mixup of rearing material (Spencer, 1976a).

Tables for all parasites per species

mod 6.iv.2018