Thursday, 19 July 2012

Plume moths

The other morning a delicate moth appeared on the kitchen window. No doubt it had entered the previous evening when the windows were flung open to draw in the cool air of dusk. The resting posture of this moth, the wings folded to a narrow horizontal, held at right angles to the body and reminiscent of a small crucifix, showed this to be a plume moth. Rather than the species that I normally encountered, this was different and more strongly marked. A quick check of my moth book confirmed it to be a beautiful plume, Amblyptilia acanthadactyla, a common species of gardens, woodland and rough ground. The larvae of this moth feed on various plants, including mints, cranesbills and hedge woundwort.

There are forty-four species of plume moth in the family Pterophoridae, plus another (the Many-plumed Moth) in the family Alucitidae. The latter, a particularly common species that is often attracted to light, is encountered in the house on an almost weekly basis throughout the summer and occasionally found hibernating in the shed during early winter.

The Pterophorid plume moths rest on long legs, that lift the moth away from the surface on which they are sat. The narrow wings vary from a flat and uniform beige through to a beautiful mix of rich ochres, yellows and browns. Some appear solid and brittle, all sharp edges and rigid lines, while others (such as the white plume moth) are softer in their appearance, with feathered trailing edges to the wings. The appearance of narrow wings is an illusion, created by the wings being folded or even rolled when at rest.

While the beautiful plume is something of a generalist when it comes to its choice of larval foodplant, many of the species are associated with just one or two foodplants. In many cases the moth takes its common name from the foodplant, as is the case with the goldenrod, yarrow and tansy plumes. Perhaps the most unusual choice of foodplant, however, goes to the sundew plume, its larvae feeding on round-leaved sundew. Not only does round-leaved sundew feed on insects but it also has something of a limited distribution within the moth’s English range – round-leaved sundew is more widely distributed in the north west of Scotland where this moth has yet to be discovered.  Sundew plume feeds on the leaves, developing seeds and flowers of the sundew.

Seeing this moth reminds me of the variety of insect life that occurs in the garden and highlights the diversity of form that is there to be seen. The beautiful plume is a moth that doesn’t look like a moth but, to my mind at least, it is certainly worthy of closer examination.

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