The larvae of the sawfly Fenusa dohrnii mine the leaves of various species of Alder (Alnus sp.). The mine takes the form of a large brownish blotch, without an initial corridor. Usually the mine starts near a vein axil, and expands towards the leaf margin. The mine mostly remains enclosed by two thick lateral veins. The adult sawfly is largely black in colour but it is the larval mines that are more regularly recorded.
Wherever Alder occurs.
When Alder is in leaf.
Widespread in Britain but infrequently recorded.
Rare or under recorded in Leicestershire and Rutland.
Leicestershire & Rutland Map
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