16 July 2023

10 July 2023 – Rise of the Yellow Underwings

There was a time, earlier in the year, when the appearance of a Yellow Underwing in the trap was scarce, but no longer. Now the various Yellow Underwings have made their presence ubiquitous: They seem to be always lurking in the deepest recesses of the trap’s egg cartons, hidden in the bark of a rotting log, or just behind the bedroom curtains, ready to fly at full speed into your face (true story).

What sets these moths apart from the others is their size and speed. Having elected to spend my entire summer handling and cataloguing moths at Shandy Hall, I do not generally think of myself as someone who is scared of bugs, especially when they are as wonderful and harmless as moths. However, when a Yellow Underwing flies into your face, it’s difficult to identify. The pure speed of the insect renders them quite alarming. They’re extraordinarily jumpy and agile, with a personality like a Heart and Dart (Agrotis exclamationis), but faster.

The Large Yellow Underwing (Noctua pronuba) was the most numerous species in the trap. I guess that we had 5 or 6, but several made their escape before we could take a photograph. Of the three that we did photograph, the range of variability in color can be observed. The marking that most clearly delineates this species from other Yellow Underwing varieties is a small, black “pip-mark” close to the leading edge of the wing. These moths are present in one protracted generation, from June to October and sometimes into November. During their peak (which, by the look of things, is fast approaching, if not already here) they come to light in huge numbers. Single Robinson traps occasionally capture several thousand Noctua pronuba in one night!

Light Arches (Apamea lithoxlaea) was a beautiful catch that I’ve not seen before. Upon first sight, I remarked that it looked like some sort of Shark, and mistook it for a Pale Pinion (Lithophane socia). These moths, common residents of Great Britain, are ultimately identifiable by their dark, ‘scythe-shaped’ markings near the center of their wings. Their genus name, Apamea, is without entomological relevance- it was simply the name of the town wherein Theodore, one of the ancient fathers of the Church, lived. The species name lithoxlaea does have a relevant meaning: ‘lithos’ (stone) and ‘xulon’ (wood) come from ancient Greek and describe the moths’ color and grain-like texturing, respectively. These moths have a sweet tooth, and are attracted to sugar more readily than they are to light. Nevertheless, they do come to light in great numbers, so I expect to see many more Light Arches in the near future.

Post : Autumn Cortright (UPenn intern)