Last week I gave you an entomological mystery to solve, in the triangular(ish) shape of this moth:

For the real insect aficionados out there, this probably wasn’t too much of a challenge (I’m looking at you Tim), but for the rest of us it wasn’t quite so easy.

The overall appearance of this moth, with its size, shape (especially wing position), and fuzzy wing fringes is what you expect from a member of the family Noctuidae – the Owlet Moths. However, it’s a big family, with almost 12,000 species. A lot of the species also look similar to each other and some have a wide variety of different colour morphs – just to make things more complicated.

Context helps us out here, since although there are of lot of Noctuidae species in the world, there are far fewer found in Ireland and there are helpful resources that illustrate them.

Even with helpful visual resources, with good photos of the different Irish species, it can be hard to work out what the diagnostic features might be. For some species of moths you have to get into the fine detail of the genitals, but thankfully there are wing patterns that are distinctive in this instance.

In this case, the wing pattern of interest is the small triangular black mark on the lower portion of the leading edge of the upper wing.

That’s it.

The rest of the colour and pattern of the upper wing is very variable in this species, so you can’t rely on any of those features as a reliable indicator. Of course, if the specimen was alive and had its wings open, it would be a much easier identification:

This is, of course, a Large Yellow Underwing Noctua pronuba (Linnaeus, 1758), which is pretty obvious once the underwing is visible. So well done to everyone who worked it out from just the upper wings.