Ulmus elm

Dichotomous table for leafminers

1a corridor mine => 2

1b blotch mine => 8

1c tentiform mine => 13

1d fleck mine => 16

1e mine ends in an oval excision => 18

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

2a corridor < 15 mm; larva chamber relatively long => 3

2b corridor > 15 mm; larva chamber relatively shorter => 5

3a corridor proportionally broad => 4

3b corridor quite slender => 5

4a corridor follows midrib and/or a thick lateral vein, unbranched; most of the corridor completely filled with frass: Bucculatrix ulmifoliae

4b corridor winding freely, with 2-4 short, frass-free side branches; frass in a central line, leaving a clear zone at either side: Bucculatrix albedinella **

5a mine very compact, corridor densely wound => 6

5b corridor in wide loops, or following a vein or the leaf margin => 7

6a larva yellow; start of corridor a dense spiral: Stigmella lemniscella

6b larva bright green; start of corridor in a number of zigzagging loops: Stigmella viscerella

7a exit slit at upper surface; frass in first part of the corridor broadly dispersed Stigmella lemniscella

7b exit slit at lower surface; frass in first part of the corridor in a narrow line: Stigmella ulmivora

8a oviposition site (generally the leaf tip) covered with a shining black drop of hardened secretion: Trachys minutus

8b no such drop => 9

9a ovipsition in the underside of the midrib of a thick lateral vein, leaving a clear scar; from there an initially narrow, later quite broad corridor running towards the leaf margin; older mines easily tearing in => 10

9b no oviposition scar, no initial corridor => 11

10a mine in May-June; oviposition generally in the midrib: Orchestes alni

10b mine in July-August; oviposition generally in a lateral vein: Orchestes betuleti

11a blotch containing generally several pink larvae; under the mine a loose spinning, in which grains of frass are hanging: Atemelia torquatella

11b blotch with 1 whitish larvae; no spinning under the mine => 12

12a on Ulmus laevis and minor; mine usually starts at the leaf magin: Fenusa altenhoferi

12b on Ulmus glabra; mine always starts in the centre of the leaf: Fenusa ulmi

13a pupa in a flimsy cocoon => 14

13b pupa in a tough, almost parchmentaceous, cocoon => 15

14a cremaster spines rather weak, outer pair bent bsckwards: Phyllonorycter agilella

14b cremaster spines very weak, out pair not bent backwrds: Phyllonorycter acaciella

15a mine short, round or oval; pupa dark brown in a greenish cocoon: Phyllonorycter schreberella

15b mine long, tube-like, between two veins; pupa light brown in a brown cocoon: Phyllonorycter tristrigella

16a lobe case: Coleophora violacea

16b composite leaf case: Coleophora serratella (youth case)

16c tubular leaf case: Coleophora serratella (final case)

16d spatulate leaf case => 17

17a case of full grown larva 9-11.5 mm: Coleophora limosipennella

17b case finally 5-6 mm: Coleophora badiipennella

18a much frass is expelled from an opening at the very beginning of the mine (mostly in a vein axil): Coleophora limosipennella (youth mine)

18b frass remains in the mine: Coleophora badiipennella (youth mine)

** Very occasionally a Stigmella can show a pathological behaviour that resembles this: pseudo-Bucculatrix“”

Not included in the key: Apterona gracilis; Ectoedemia preisseckeri; Orchestes quedenfeldtii; Stigmella ulmiphaga.

mod 9.x.2017