Butterfly of month - Small Tortoiseshell

If you have seen Small Tortoiseshell butterflies earlier in the year, they will have been the ones that have flown after winter hibernation and may have, therefore, been damaged and rather less colourful than those that you will see in July.

The females will have laid between 60 - 100 eggs on the tender leaves of Stinging Nettles, growing
in sunny spots, early in May. These will have hatched after about 10-14 days and you may have seen the dense silken webs that the black and yellow caterpillars spin around the leaf tips to live communally until they have made their last skin change. Then they disperse and some of the beautiful gold or brown chrysalides have been found as far away as 60 yards from the nearest nettles, suspended from other plants or materials.

A few butterflies from this generation may emerge towards the end of June, but July is the month to watch out for them in the Blackwater Valley. You may come across the Small Tortoiseshell almost anywhere in the Valley, with so many patches of Stinging Nettles being left in sunny spots by the “conservation-minded”.

Their upper wings have a mixture of orange, yellow and black, with dark edges usually showing some blue. The underside forewings are lighter than the hindwings, which provided a darker camouflage when the butterflies are resting with their wings closed. When open, their wingspan is about 45 mm (1.8 in). You may see them posing with wings open, whilst nectaring on Devil’s-bit Scabious, Field Scabious, Small Scabious or other flowers. The over-wintering generation, which fly from late August onwards, often nectar on Hemp Agrimony, Buddleia, Michaelmas Daisies and Sedum.

In Scotland, in the past, the Small Tortoiseshell has been known as the “Devil’s butterfly” or the “Witch’s butterfly”. People in other parts of the British Isles have called them the “Tortoise-shell fly” or the “Nettle Tortoiseshell”.

Peter Martin

Peter Martin is the author of Blackwater Valley Butterflies a handy A5-sized full-colour guide giving details about all the 32 different butterfly species you are likely to come across in the Valley.                                                                  More details >>>

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