TRIGONELLA. Fenugreeks. [Fabaceae]

Twenty-one species of Trigonella are recorded in Britain. All are introduced and include Blue Fenugreek (T. caerulea), Sickle-fruited Fenugreek (T. corniculata), Fenugreek (T. foenum-graecum), Egyptian Fenugreek (T. hamosa) and Star-fruited Fenugreek (T. monspeliaca).

Only one Diptera miner, the polyphagous drosophilid Scaptomyza graminum, is recorded on Trigonella in Britain.

The polyphagous agromyzid Liriomyza trifolii has been recorded in quarantine in Britain (Pitkin and Plant in British leafminers).

Elsewhere the agromyzids Agromyza nana, Chromatomyia horticola, Liriomyza bryoniae, Liriomyza congesta, Liriomyza strigata and Liriomyza trifolii are recorded mining Trigonella.

No non-Diptera miners are recorded on Trigonella in Britain.

Elsewhere two British non-Diptera miners are recorded on Trigonella (see below).

Note: Diptera larvae may live in a corridor mine, a corridor-blotch mine, or a blotch mine, but never in a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Pupation never in a cocoon. All mining Diptera larvae 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. The larvae lie on their sides within the mine and use their pick-like mouthparts to feed on plant tissue. In some corridor miners frass may lie in two rows on alternate sides of the mine. In order to vacate the mine the fully grown larva cuts an exit slit, which is usually semi-circular (see Liriomyza huidobrensis video). The pupa is 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).

1 > Corridor-blotch mine. Mine begins as a normally upper surface deep corridor and becomes a blotch lying centrally in the leaf, often touching the leaf petiole, if leaves are small larva may mine across the stem to another leaf. Frass partly in grains or streaks but mainly in clumps towards margins of blotch. Pupation internal or external, sometimes in a separate pupation mine.

On numerous plants in several genera and families in Britain and elsewhere. Widespread in Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe and also recorded in Asia and North Africa.

Scaptomyza graminum (Fallén, 1823) [Diptera: Drosophilidae].

Key for the identification of the mines of British
non-Diptera recorded on Trigonella

Note: The larvae of mining Coleoptera, Hymenoptera and Lepidoptera may live in a corridor mine, a corridor-blotch mine, a blotch mine, a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Larva may pupate in a silk cocoon. The larva may have at least six legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles (see video of a gracillarid larva feeding). Larvae of Hymenoptera and Lepidoptera usually also have abdominal legs (see examples). Frass, if present, never in two rows. Unless feeding externally from within a case the larva usually vacates the mine by chewing an exit hole. Pupa with visible head appendages, wings and legs which lie in sheaths (see examples).

1a > The first generation initially forms an unmistakable leaf-mine on Anthyllis vulneraria, but the second generation feeds on the flowers. Feeding signs on other plants vary in appearance. Larvae can move between sewn leaves, and more than one larva may be found together (UKMoths). Larvae in a small full depth blotch, often with extensions. Frass concentrated in one corner of the mine. The mining activities may cause the leaf to roll inwards. Older larvae live free among spun leaves, but still they may make then full depth mines by feeding on the leaf tissue from a small opening (Bladmineerders van Europa).

Recorded on Anthyllis, Medicago, Onobrychis, Ononis and Trifolium, but not yet on Trigonella, in Britain and Anthyllis, Chamaecytisus, Coronilla, Cysisus, Dorycnium, Galega, Glycine, Hymenocarpus, Lathyrus , Lotus, Medicago, Melilotus, Onobrychis, Ononis, Ornithopus, Oxytropis, Phaseolus, Psoralea, Trifolium, Trigonella and Vicia elsewhere. Britain including the Channel Is. and Northern Ireland. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Aproaerema anthyllidella (Hübner, 1813) [Lepidoptera: Gelechiidae]

1b > Leaf-miner: In the first instar the larva mines the leaves, forming short, irregular, blotch-like mines, but in later instars it lives externally, feeding in spun leaves and often twisting those of tender shoots. Larval head light-brown or yellowish brown, edged with black postero-laterally, ocellar area blackish; prothoracic plate black edged with whitish anteriorly; abdomen dull dark green; pinacula distinct, black, sometimes brownish but with black bases to setae; anal plate large, black (Bradley et al., 1973). Small, full depth mine without a definite shape; little frass. Some silk is deposited in the mine. The larva soon leaves the mine and continues feeding among spun leaves (Bladmineerders van Europa).

Recorded on numerous genera and species of several plant families, but not yet on Trigonella, in Britain. Recorded on numerous genera and species of several plant families, including Trigonella, elsewhere. Widespread in Britain and continental Europe. Also recorded from the Channel Is.

Cnephasia incertana (Treitschke, 1835) [Lepidoptera: Tortricidae]