The leaf and stem mines of British flies and other insects
 

(Coleoptera, Diptera, Hymenoptera and Lepidoptera)

by Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds

  

POLYSTICHUM. Shield-ferns and Sword-fern. [Dryopteridaceae]

Four species of Polystichum are recorded in Britain. These include the native Hard Shield-fern (P. aculeatum), Holly-fern (P. lonchitis) and Soft Shield-fern (P. setiferum). The BSBI provide a downloadable plant crib for Polystichum.

Holly-fern (P. lonchitis) is protected in Northern Ireland under Schedule 8 of the Wildlife (Northern Ireland) Order, 1985.

Three British miners are recorded on Polystichum.

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

1a > Leaf-miner: Large full depth blotch, covering the entire distal part of a pinnula. The mine begins near the top, where an elliptic egg shell is attached to the underside of the rachis. Larva solitary. The mine contains much frass.

An upperside blotch at the tip of a pinna lobe.

On Pteridium and Dryopteris, but not yet on Polystichum, in Britain and continental Europe and additional other genera of ferns elsewhere. Widespread in Britain and continental Europe. Also recorded in East Palaearctic and Near East.

Chirosia histricina Rondani, 1866 [Diptera: Anthomyiidae].

1b > Leaf-miner: Larvae usually feed on the underside of a fern frond under an untidy mass of sporangia, but on occasion enter the leaf to make an extensive irregular blotch mine. Usually the larva lives free under the leaf, under an inrregular mass of spun soredia and frass. The larva feeds on the sori, and larva betrays its presence as a sorus on an unusual place. Sometimes also elongate full depth blotches are made.

On Asplenium, Phyllitis, Polystichum and Dryopteris in Britain and Asplenium, Ceterach, Phyllitis, Polystichum and Dryopteris elsewhere. Widespread in southern England and Wales. Initially occurred mainly near coasts, but it is increasingly recorded inland. Outside of Britain and Northern Ireland, only recorded in Madeira.

Psychoides filicivora (Meyrick, 1937) [Lepidoptera: Tineidae].

1c > Leaf-miner: Full-depth corridor or blotch, often positioned along the leaf margin. In the first part much, brown-black, fine-grained frass, later parts of the mine almost free from frass. After hibernation the larva lives free in an untidy case of silk, covered with remants of sori.

On Asplenium, Ceterach, Phyllitis and Polystichum in Britain and Asplenium, Ceterach, Phyllitis, Pteridium and Dryopteris elsewhere. Widespread in Britain and continental Europe.

Psychoides verhuella Bruand, 1853 [Lepidoptera: Tineidae].

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