Why The Satellite?

A noctuid moth turned up on the kitchen window yesterday that was identified (after some difficulty) as a satellite (Eupsilia transversa).

The English name comes from the small spot on each forewing which has usually two satellite spots beside it.  In this close up picture one satellite is quite clear, but the other, to the south west of the orange main spot, is very faint.

The moth is quite common in the British Isles and overwinters as an adult.