Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Origanum

1a > Leaf-miner: Mine beginning with small spiral, followed by a linear section to the margin of the leaf where a dark blotch is formed. Pupation internal (Spencer, 1972b: 86 (fig. 292), 90; Spencer, 1976: 464, 465 (fig. 813)).

Essentially a corridor mine. It begins as a tiny upper-surface spiral. The corridor at this point is so narrow and closely wound that it rather resembles a simple spot. Next follows a simple corridor running towards the leaf tip, often following the leaf margin for some distance. In the leaf apex a quite long corridor is made, while the mine is laid in loops that are so close that a secondary blotch results, with prominent secondary feeding lines. The final section of the mine again is a simple corridor, in the end of which pupation takes place. Before pupating the larva already has made a semicircular slit in the epidermis. Not infrequently the puparium falls out (Hering, 1957).

The initial mine is a small spiral. The mine then follows the edge of the leaf and a dark blotch is formed. Pupation is within the mine.

On Origanum vulgare in Britain and elsewhere. Widespread at least in south of Britain. Also recorded in the Republic of Ireland and Widespread in continental Europe.

Phytomyza origani Hering, 1931 [Diptera: Agromyzidae].

1b > Leaf-miner and case-bearer: Blotch mines reaching the edge of the leaf, initially pale green turning brownish white, are caused by the larva feeding on the underside of a leaf. The fully developed case is slender, shining black brown, about 9 mm long. Towards the end a narrow, transparent yellowish ventral keel. Mouth angle 50-60°. Cases on the leaf underside.

On Calamintha, Clinopodium, Glechoma, ? Lycopus, Mentha, Nepeta, Origanum, Prunella, Salvia, Stachys and Thymus in Britain plus Melissa, Melittis and Satureja, but not Calamintha, elsewhere. Throughout England and Wales and a few places in Scotland. Widespread in continental Europe.

Coleophora albitarsella Zeller, 1849 [Lepidoptera: Coleophoridae].