Centaurea knapweed, cornflower
Incl. Cnicus, Colymbada, Cyanus, Jacea, Mantisalca.
(For a dichotomous table for galls on Centaurea by Hans Roskam click here)
Dichotomous table for leafminers
Dichotomous table for leafminers
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 mijn _in_ the, somewhat discoloured, midrib: Ceratapion austriacum
10b mine centered on the midrib, or ending there => 11
10c 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 or 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).