I often find the large caterpillars of this moth in the spring after the larvae have spent the winter in hibernation feeding on reads alongside the River Itchen in Hampshire, UK. The Drinker moth gets its name from the larvae drinking droplets of rainwater. When alarmed the large caterpillars curl up into a ball protected by their hairs which are quite irritable. The caterpillar also mixes its hairs into their cocoons to protect the pupae inside. I know from experience rearing and handling the cocoons of this species for photography many years ago left me with a rash on my hands. Moths are on the wing from July to August.
The caterpillars feed on grasses and reeds and grow to quite a large size compared to the resulting moths. I have found full grown caterpillars sunning themselves in on tree branches, barbwire, bramble bushes and tree barks. The moth is also interesting to photograph with the shrew-like appearance of its head.