Commas confirmed breeding in South West Scotland

In recent years we've seen a significant increase in the number of Comma sightings in SW Scotland. Until now these records have all been of adult commas, but thanks to Heather Young of the SW Scotland branch we now have proof of Commas breeding in the branch area.Comma Caterpillar

On the 13th of July, Heather found this nearly full grown caterpillar on an elm near Bridge of Allan, Stirlingshire (NS788988). She suspects it was wych elm, but is having the elm species confirmed by a botanist to be sure. The caterpillar began to pupate a just few days later.

There have been only 2 other records of comma caterpillars in Scotland in recent times. On both occasions they were in the Borders. The first was seen in 2006 at Sprouston near Kelso, on elm, and the second at Duns in early July 2010, on nettle.

The Comma caterpillar is quite distinctive, with a large white patch at the rear of the body which gives them the appearance of a bird's dropping. The mature caterpillar will sit happily on the upper surface of leaves, trusting in their bird-dropping mimicry to keep them safe from predators. In England and Wales comma caterpillars can be found on stinging nettles, elm, wych elm, hops and occasionally currents. The pupa resembles a dried leaf dangling from the food plant and is much harder to find!

If you are out for a walk and pass patches of nettles or a stand of elms in SW Scotland keep an eye out for Comma caterpillars (and adults!) and let us know.

Heather Young & Scott Shanks

Caterpillar photograph (c) Heather Young 2010.