Marsh mallow moth  (Hydraecia osseola hucherardi)

The common name of the Marsh Mallow moth refers to the larval (caterpillar) foodplant of the same name (Althaea officinalis). Adults are dark cream in colour (3) with paler hindwings (2).

Following a decline that started in 1966 (3), this moth is currently restricted to three sites in the Romney Marsh to Rye area on the border between Sussex and Kent, and a site in Kent on the bank of the river Medway (4). In Europe, the species occurs in only a few scattered sites (1).

The foodplant, marsh mallow, grows in damp, low-lying places along watercourses, field margins and ditches (4).

Adults of this single-brooded species are active at night in September; caterpillars are present from early spring to July and feed on marsh mallow roots. The overwintering stage is the egg (2).

The main reason for the decline of this species seems to be loss of the foodplant resulting from repeated mechanised ditch clearance, drainage, herbicide use and overgrazing (1). In addition to this, the Marsh Mallow moth is at the limit of its range in Britain, which may make it vulnerable to climatic factors (3).

The Marsh Mallow moth has been targeted by the UK BAP (Biodiversity Action Plan) as a priority for conservation action. Both remaining populations occur within Sites of Special Scientific Interest (SSSIs), and the population of the marsh mallow foodplant has been supplemented with reintroductions that may allow the moth population to increase (1).

Further reading on moths:
Skinner, B. (1998) Colour Identification Guide to Moths of the British Isles. Viking Press, London.
Leverton, R. (2001) Enjoying moths. Poyser, London.

Information authenticated by Sean Clancy.