Huge Decline in Small Tortoiseshell Butterfly Number Baffles Scientists
The Small Tortoiseshell butterfly was common in gardens throughout the UK, but in recent years it has a suffered dramatic decline, especially in South East England where its numbers are down by over 80 per cent since 1990. The fact that losses are greater in South East England suggests that the problem may be linked to climate change.
Parasite Fly
Another suspect is the tiny parasitoid fly Sturmia bella, first noted in Britain in 1999. Its arrival from Southern Europe is either the result of climate change or an unwitting introduction from caterpillars brought in from Europe. The charity Butterfly Conservation has launched a research project with Oxford University’s Department of Zoology to determine the extent, if any, that the fly is to blame.
Parasite Fly
Another suspect is the tiny parasitoid fly Sturmia bella, first noted in Britain in 1999. Its arrival from Southern Europe is either the result of climate change or an unwitting introduction from caterpillars brought in from Europe. The charity Butterfly Conservation has launched a research project with Oxford University’s Department of Zoology to determine the extent, if any, that the fly is to blame.
Sturmia bella eggs are increasingly found on the nettles that the Small Tortoiseshell’s caterpillars feed on. It is suspected that the caterpillars are consuming the eggs which then hatch and develop inside them as they reach the cocoon stage, killing the host.
Dr Martin Warren, Chief Executive of Butterfly Conservation, said: ‘We are deeply concerned about the decline of the Small Tortoiseshell and are desperate to find the causes. Butterflies are great indicators, telling us much about climate change and the state of the environment. However, there are times like this when we need experts to interpret what they are telling us. In this case there may be a serious message about unexpected consequences of global warming.’
Hundreds of Butterfly Conservation volunteers are expected to help the Oxford research team by collecting batches of Small Tortoiseshell caterpillars.
Dr Warren said: ‘It is only after we get to the bottom of this that we can try to devise a strategy to save the Small Tortoiseshell.’
Courtesy of Butterfly Conservation.
Dr Martin Warren, Chief Executive of Butterfly Conservation, said: ‘We are deeply concerned about the decline of the Small Tortoiseshell and are desperate to find the causes. Butterflies are great indicators, telling us much about climate change and the state of the environment. However, there are times like this when we need experts to interpret what they are telling us. In this case there may be a serious message about unexpected consequences of global warming.’
Hundreds of Butterfly Conservation volunteers are expected to help the Oxford research team by collecting batches of Small Tortoiseshell caterpillars.
Dr Warren said: ‘It is only after we get to the bottom of this that we can try to devise a strategy to save the Small Tortoiseshell.’
Courtesy of Butterfly Conservation.
Read the comments about this article and leave your own comment
A small tortoiseshell was my first butterfly of the year in the garden this year. But only one so far. The past few years they seem to have been replaced by commas, which I love too, but it would be good to see lots of both.
I've also seen orange tips and holly blues so far in the garden this year.
Let's hope the dry early spring has been beneficial to butterflies and given them a good start.
Posted by: Dave Wilcox | 15 Apr 2011 23:37:54
Normally on the buddleia in my garden there are 6 or 7 at a time ,but today I have only seen one .
Posted by: jimmy king | 01 Aug 2010 22:00:17
I have a garden with everything that tortoiseshells need. nettles, nectar plants, hibernation towers, ivy, sheds etc etc even a meadow but no tortoiseshells no peacocks some whites a blue and some migrants but no good old british butterflies it has taken me years to build up a really good butterfly garden I am disappointed any suggestions welcome
best wishes
mike
Posted by: mike dempsey | 30 Apr 2010 20:25:13
I have been overjoyed this year after seeing none for many years to see on a number of occasions tortoiseshell butterflies on the sill outside my bedroom window. Why are they here this year? Well it seems that the thing which has aggravated my neighbour all summer has been perfect for the butterflies. I left the nettle bed in my vegetable garden and allowed them to just be all summer. I was asked by a relative the other day why I had done nothing with them and I said, this year we have tortoiseshells and they are in trouble so the nettles can stay and we will live with them for now.
The butterflies matter and it is joyous to see them back
Posted by: Bernadette Morgan | 09 Sep 2009 23:48:50