Moths in December from Mary Atkinson

The Gem moth, female.

Part of the unsettled weather we are having at present is giving us pulses of warm air coming up from the south, bringing some migrants, particularly to the southern part of Cornwall. Apart from the usual trickle of Rusty-dot pearls and Dark Swordgrass, there’s always a chance of less usual species, for example the Gem which will come to light. Widespread on the continent, it is a great wanderer. The sexes are dimorphic as shown in the pictures.

Gem moth, male.
Dark Chestnut.

Dark Chestnut, less common than the Chestnut, this richly coloured moth, aptly described by its name, can be seen at light or often feeding on late ivy flowers. Different clumps of ivy open at different times in the autumn, thus giving an extended season when insects are able to nectar on this valuable food source.

The Dark Chestnut is single-brooded, appearing from November to February, and can be differentiated from the Chestnut because the tips of the fore-wing are pointed or even slightly hooked. See pictures. Care is needed however,  because worn specimens may well have this feature abraded and less obvious. The leading edge of the Chestnut wing is rather fuller and slightly rounded. Practice helps.


The books say that the Dark Chestnut can be commoner than the Chestnut but I don’t find that is the case here in east Cornwall, although both species are increasing their distribution throughout the UK. Bear in mind that increased moth trapping even through the winter months when these moths fly, may have some effect on the numbers of records collected.

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