Reddish buff moth  (Acosmetia caliginosa)

The Reddish Buff moth's name provides a good description of the adult. It is a night-flying moth and hides up in vegetation during daylight hours. The caterpillars are bright green with yellow stripes and are found in July and August on their food plant, saw-wort.

Once found in the New Forest and parts of Hampshire, since 1960 the reddish buff moth has been confined to one site on the Isle of Wight. This consists of two fragments of heath land.

The moth requires sites that receive enough sunshine to encourage saw-wort, its food plant, to grow. Saw-wort grows on a variety of habitats including damp grassland, fen margins, heaths and woodland rides.

Having laid its eggs on saw-wort, the moth's caterpillars feed on the plant before spending the winter just below ground as pupae. The adult moth emerges in late May to early June and, like most moths, is nocturnal. It hides by day in long grass or other vegetation and will only fly if disturbed.

Much of the decline in numbers has been due to changes in the habitat preferred by the reddish buff moth. The sites where the moth was formally found have been planted with conifer crops, which has shaded out the saw-wort and resulted in the loss of reddish buff moths from the UK mainland. Elsewhere, neglect of sites has allowed scrub to predominate and in these conditions the moth cannot survive.

This species had declined to such a level that it has been added to the Wildlife and Countryside Act. English Nature's Species Recovery Programme has encouraged careful and accurate monitoring of the numbers remaining at the one site and has ensured that the habitat is managed in a viable way. Light-trapping and release of adult moths is undertaken each year to gain some idea of existing numbers. Re-introduction of moths to former sites in Hampshire and the Isle of Wight is currently in progress. A captive-breeding project is underway to maximise the survival rate of the pupae and provide larvae for the re-introduction programme.