A dot moth (Melanchra persicariae) caterpillar on a spindle tree, seen and photographed by DKG while the FoSCP volunteers cleared the undergrowth around the young trees at the top of Sheep Field. Spindle is not recorded as one of this caterpillar’s food plants, but sallow is, and hazel, nettles, docks and several other species growing in that plantation and its understorey.
We thought at first, because of its colour and the diagonal stripes on its sides, that we had found the larva of some sort of hawk moth. It took a while and a lot of googling to correctly identify it. Dot moth caterpillars come in a range of colours from green, through a variety of browns to pinkish purple but in all colours they are distinguished by three pale lines across the prothorax, which is the segment which bears the first pair of legs. The three lines are clearly visible in the middle photograph.
The adult moths lay their eggs on food plants from July onward and the eggs hatch into caterpillars after about 30 days. The caterpillars are fully grown, up to 45 mm, in 28 days. The one we found this morning, which was quite large, may well have been ready to pupate; one of the earliest to do so. Dot moth caterpillars are found from August right through until October.
They overwinter as shiny brown pupae in the soil, usually under leaf litter, and emerge as adults in the spring.
Photographs: caterpillar by DKG; adult by Ben Sale (CC2.0)