Most people think of moths as annoying pests that damage woollen and cotton clothes, or insects that are attracted to light, but there is one British variety with a caterpillar with a most unusual habit because it likes to drink drops of rain or dew. The adult is aptly named The Drinker, and even its scientific name, Philudoria potatoria, refers to this.

This fascinating insect is in the Lasciocampidae family of moths, which also includes the large Oak Eggar (Lasiocampa quercus) and Lappet Moths (Phyllodesma ilicifolia). These species have interesting larvae too that are very big.

I was fascinated by the caterpillars of the Drinker Moth when I first encountered them as a boy. My parents used to take me out in the car to various locations in the countryside and that is where I would find Drinker caterpillars. I was fascinated by their unusual habits and loved their furry coats and the way they would curl up if touched.

Caterpillar of the Drinker Moth

Drinker Moth larva
Credit: Photo by Steve Andrews

The caterpillar is large when full-grown in June and it is found along roadsides, on marshland and moors, on sand dunes and in other places in which grass and reeds, on which it feeds, are found.

Its body is a dark slaty-grey colour and has 2 rows of small yellow dots and dashes running parallel to each other down its back.

The caterpillar is very hairy and has 2 tufts of longer brown hair, with one at the head pointing forward and the other near the tail pointing backward. 2 lines of shorter black tufts run just inside the lines of yellow marks, and lower down on each of the sides of the body are further lines of shaggy yellowish and white hairs.

The Drinker caterpillar is quite a pretty creature in its own way and is not easily confused with other larvae. When it curls up if disturbed, like the one in the photo I have included, it looks like a furry wheel to me! Many species of caterpillar will curl themselves up if disturbed but there are no other moth larave that I know of that will drink water.

It pupates in a long whitish or yellowish-brown cocoon, which is attached to a grass stalk or reed stem. The adult moth emerges in July and the smaller male is usually a light chestnut brown colour, whilst the female is a yellowish-buff.

There is considerable variation in the colouring of moths found and sometimes it is the females that have the darker brown.

The eggs are laid on the food-plants and the young caterpillars feed until late September or October when they go into hibernation.

The following April they start to wake up and to commence eating again. When they are large, on a very still and quiet night, it is possible to hear them munching away at a blade of grass or a juicy reed. Imagine that, listening to caterpillars enjoying a meal after dark!

Copyright © 2012 Steve Andrews. All Rights Reserved.

A living Drinker Moth caterpillar can be seen in this video