Each week I try to out out the moth trap on the lawn. I don’t always succeed, with work and weather conspiring together to prevent me doing so. But on the last day in May I was at home, and despite the rain I decided to try and see what was on the wing. The catch wasn’t huge, but there were 2 new species for the garden, so I count that a success. I’ve now identified 105 species in the garden.
After this catch the Lobster Moth, Stauropus fagi, is now one of my new favourites. Some guides describe it as unassuming, but I think this is rather unfair as it’s rather handsome. But to be fair, the adult is not as striking as the larva which has influenced its name.
S.fagi is a member of the Notodontidae, or Prominent and Kitten Moths. There are over 2500 species world Wilde, of which 28 have been recorded in the UK. 22 are resident, and the others are rare migrants. The Notodontidae are all furry, thick bodied moths. The caterpillars are often unusual, not least that of S.fagi. The more I read about this the more I want to find one. But more on the larva later. S. fagi has a characteristic resting pose with the hind wings protruding from under the edges of the forewing.
The forewing is between 24-33mm, and has a wingspan of between 45-60mm. The colouration of wings are cryptic, creating a camouflage of grey-brown along with a dusting of grey. This allows it to blend in to the bark of trees when resting during the day. As an adult S.fagi is unable to feed and is rarely seen by day, probably helped by its camouflage.
But it is the caterpillars, or larvae that hold a fascination, and can be found between July and September. With a reddish-brown appearance the whole body is covered in small dimples. The head looks like an alien from a poor Hollywood B movie, and an enlarged anal segment with two stick-like brown coloured claspers. It also has thorn-like bumps on four of the mid-body sections. As if it wasn’t weird enough to look at, when disturbed the caterpillar folds the swollen rear section over the rest of its body, and it waves its long legs in the air. The whole ensemble leads to it’s common name of lobster moth. Here’s a link to a short YouTube video showing it’s defensive action: https://m.youtube.com/watch?v=V1wV9P-f7Dc
The larvae live on the leaves of beech (Fagus), oak (Quercus), and several other trees.
Once it has matured enough and finished feeding it pupates over winter in a cocoon spun among leaves or in the soil.
S.fagi is resident in the UK, but seems to be more frequent in the south, but even in these areas it doesn’t seem to especially common.
Now for a little etymology. Stauropus comes from Greek stauros = cross, and pous = foot, and probably refers to the anal segments of the larva when it is raised in defence. Fagi refers too the beech, one of it’s food plants. In Welsh it is called Llwyd Ffawydd
Hoskins, A. Stauropus fagi. http://www.learnaboutbutterflies.com/Caterpillar%20-%20Stauropus%20fagi.htm. Accessed 2017.06.19
National Biodiversity Network. Stauropus fagi – NBN. https://species.nbnatlas.org/species/NBNSYS0000006085. Accessed 2017.06.19