Black-veined White (Aporia craetagi) Photo By Sven Damerow – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=90638361

Dear Readers, whilst some butterflies that were previously extinct in the UK are now, as the climate warms, crossing the Channel and re-establishing themselves, this was never going to happen with the beautiful Black-veined White (Aporia craetagi). The males are occasionally seen in coastal areas of the UK, but the females only venture about 1 km from the spot where they emerged as adults. So, a combination of the good folks at Knepp (famous for spearheading  rewilding), Dartmoor Zoo, Butterfly Conservation, Royal Holloway University and the veterinarians at the Zoological Society of London (ZSL) have been working to reintroduce the species.

Black-veined whites went extinct in the UK about 120 years  ago,  due to the loss of habitat, the intensification of agriculture and a series of bitterly cold winters. The caterpillars feed on hawthorn and blackthorn, but the grubbing up of so many hedgerows was probably another blow. So, female butterflies have been carefully collected in Spain, and have been brought back to the UK, where they’ve laid their eggs on suitable foodplants, and where the tiny new caterpillars will overwinter on communal webs. The folk at Knepp will have an anxious time waiting to see if the caterpillars  thrive, and protecting them from predators. You can listen to a podcast on the subject here.

Black-veined White caterpillar (Photo By James Lindsey at Ecology of Commanster, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1680592)

The role of ZSL was to assess the disease risk from re-introducing the butterfly – would its presence impact on other insects or plants? The risk was found to be very low. However, there is a risk to the butterflies themselves from flies and parasitoid wasps. These risks are most intense during the early stages of the project – the new caterpillars will be protected by mesh which should be fine enough to keep even tiny flying insects out, and those looking after them will use disinfection and protective clothing. The plants that the caterpillars feed on have been carefully checked for wasps and flies, and cultivars that seem to attract these parasites will be avoided.

Mating Black-veined Whites (Photo By Hectonichus – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=56238615)

I look forward to seeing how this project goes. How wonderful it would be to see these beauties in the wild again! Apparently the adults love purple/red flowers, particularly red clover, so let’s get planting….