Elymus, couch-grass

Dichotomous table for leafminers

incl. Agropyron, Elytrigia, Hordelymus, Leymus, Roegneria, Sitanion; Thinopyrum intermedium = Elymus hispidus = Elytrigia intermedia

1a fleck mine: Coleophora lixella

1b corridor or blotch => 2

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

2a larva with chitinised head; in narrow parts of the mine the frass lies in a central line => 3

2b larva a maggot; in narrow parts the frass in two rows along the sides => 5

3a larva: rear margin of head excised in a deep V; terminal segment with a pair of spine-like spiracula: Hispa atra

3b rear margin of head not excised; no such spiracula => 4

4a recorded from Leymus arenarius (Lyme-grass): Elachista argentella, littoricola

4b recorded from Elymus caninus (Bearded Couch): Elachista adscitella, apicipunctella

4c recorded from Elymus repens (Scutch): Elachista albifrontella, argentella, cingillella, griseella, littoricola, maculicerusella, pollinariella, pullicomella

4d recorded from Elymus hispidus: Elachista pollutella

4e recorded from Hordelymus europaeus: Elachista obliquella

5a larva: mandible with 1 tooth; mine usually begins in a leaf sheath; there, at the outside, an egg shell: Hydrellia griseola

5b mandible with at least 2 teeth; mine begins in the blade; no egg shell => 6

6a pupation outside the mine => 7

6b puparium within the mine => 11

7a larva: cephalic skeleton of Agromyzinae-type => 8 *

7b cephalic skeleton of Phytomyzinae-type => 9

8a larva: bands of spinulation on the segments unusually wide; on abd 8 the spinulation occupies dorsally the entire width of the segment: Agromyza nigrociliata

8b bands of spinaluation smaller: Agromyza rondensis

9a larva and puparium set with long spine-like papillae: Pseudonapomyza atra

9b larva nor puparium with such spines => 10

10a mine a narrow corridor; larva: rear spiraculum with 3 papillae: Liriomyza flaveola

10b mine broad; rear spiraculum with over 10 papillae: Cerodontha flavocingulata

11a puparium: spiracula penetrate the epidermis => 12

11b puparium not in contact with the outside world => 13

12a puparium orange brown: Chromatomyia nigra

12b puparium black: Cerodontha muscina

13a mine begins in the leaf blade, descending from there into the leaf sheath: Cerodontha denticornis

13b mine remains in the blade => 14

14a rear spiracula on two high diverging cones: Cerodontha calosoma

14b rear spiracula on a broad common base => 15

15a rearwards pointing arms of the cephalic skeleton largely dark; puparium without silken strand; larva solitary => 16

15b these arms transparant; puparia anchored in the mine with a silken strand; larvae communal => 17

16a puparium: rear spiracula seen from above form a V: Cerodontha lateralis

16b they form a U: Cerodontha superciliosa

17a larva: the black warts at the outside of the rear spiracula small, without a “root”: Cerodontha incisa

17b these warts large, with a deep “root”: Cerodontha pygmaea

* See also the key to grass-inhabiting Agromyza larvae.

Not included in the key: Aphanisticus pygmaeus; Cerodontha spencerae, zuskai; Elachista fasciola; Ochsenheimeria urella, vaccuella.

mod 9.x.2017