Saturday, 14 November 2020

5th. In the series ‘One to look out for’, the Northern Winter Moth

Over the past couple of years, I have been highlighting some species found in Montgomeryshire in the 'one to look out for' series, which are either uncommon or are confused with other species, today I’m looking at the rather elusive Northern Winter Moth.

The Northern Winter moth is definitely a species which is overlooked by moth-ers in general, either because of its flight season, which as its name suggests is a winter flying species, secondly because it’s often confused with the Winter Moth and finally it is generally much more uncommon than the Winter Moth here in Montgomeryshire, therefore you normally have to put in a bit more effort in to record it. In the past ten years it has only been recorded at seven sites in Montgomeryshire, but I think this figure could be significantly increased with more recording. 

There are some subtle differences between the two species which I’ll outline here and these should help you to separate the two species with a fairly high degree of certainty.

                                        Northern Winter Moth - Operophtera fagata

                                               Winter Moth - Operophtera brumata

As can be seen from the two images above (only the males are shown for this comparison, the females only have vestigial wings and therefore can’t fly) the Northern Winter Moth (top) is somewhat larger than the Winter Moth (bottom) with a more tapered forewing, it is also paler with more fine markings and has a general silky sheen to the eye.

It’s on the wing from late October until December and the males are attracted to light traps. When the females emerge they will just climb up the nearest tree or bush, release their irresistible pheromones and wait for a male to come along and mate with her. Eggs are laid on the foodplant where they  overwinter until they hatch in the spring. The larvae feed on a number of deciduous tree species which include; Birch, Alder, Beech and has also been found on some fruit trees; Apple, Plum and Cherry. It’s found in various habitats, such as woodland, heathland and gardens. It pupates underground.


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