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

1b > Leaf miner: A short white mine. Pupation in mine (Spencer, 1976: 217, 219 (fig. 376)).

Irregular corridor, essentially parallel to the leaf blade. Mine white when seen from above, uniformly greenish when seen by transparency. Frass in one, rarely more, big black lump. Larva solitary. Pupation in the mine; puparium parallel to the leaf venation.

Short, longitudinal blotches - often coalescing to make longer mines or wider mines or both.

On Iris pseudacorus in Britain and elsewhere. Widespread and common throughout Britain from Banff to Scilly Isles. Also recorded in the Republic of Ireland. Widespread in continental Europe. Also recorded from the East Palaearctic and the Oriental Region.

Cerodontha iraeos (Robineau-Desvoidy, 1851) [Diptera: Agromyzidae].

1c > Leaf miner: A number of larvae feeding together to form a conspicuous, mottled greenish mine. Pupation laterally across the leaf at end of mine (Spencer, 1972b: 100).

Two to 12 eggs are separately inserted in a leaf, not far from the apex. The young larvae begin making a short, narrow, corridor that runs upwards. Soon the direction reverses, the corridors quickly become wider and fuse. The result is a large blotchy mine, generally containing several larvae. The mine is very inconstant in depth, making it vary, when seen by transparency, from green to almost vitreous. Mines contain several lumps of frass. Pupation in the mine. The pupariria lie close together in a row, in the lowest part of the mine, oriented perpendicularly to the leaf.

Forms a blotch mine, which may be large when several mines coalesce.

On Iris foetidissima, Iris ochroleuca and Iris spuria in Britain and Iris foetidissima and Iris ochroleuca elsewhere. Abundant throughout southern counties of Britain. Widespread in western Europe.

Cerodontha iridis (Hendel, 1928) [Diptera: Agromyzidae].