www.ukbutterflies.co.uk

To my knowledge, no UK species of butterfly is reliant on Ash for its larval foodplant.

That said, most of us know that this British 'bedrock' tree is a focal point for many of our butterflies, particularly Hairstreaks.

I was surprised to hear that Ash represents as much as 30% of all British trees. I was even more surprised (alarmed, even) to read that 90% of Denmark's native ash growth has been wiped out by the dreadful disease this article refers to:

http://www.bbc.co.uk/news/science-environment-20079657

Could this be another natural event akin to the decimation of our Elm trees during the 20th Century?

"A disease that has the potential to devastate the UK's ash tree population has been recorded for the first time in the UK's natural environment.

Chalara dieback, caused by a fungus called Chalara fraxinea, was confirmed at two sites in East Anglia.

Until now, the disease had only been recorded in a few nursery specimens.

Ash trees suffering with C. fraxinea have been found across mainland Europe, with Denmark reporting the disease has wiped out about 90% of its ash trees".

Worrying times, for sure.

Yes David,
That is a very rapid spread and a fungus is not the easiest thing to stop once it gets a foothold, so it is not looking good. There may be no British butterfly which uses Ash as a foodplant, but it is definitely on the menu for a number of moths including Privet Hawk moths. After problems with our Horse Chestnut and Oak over recent years, it seems that each season brings bad news for yet another native species of tree.

Trev

For butterflies, this may not be bad news - it will serve to let light into woodlands, many of which are too dark at present, which should allow for regeneration of our woodland flora and provide a boost for some of our struggling woodland species.

I don't understand why we have been importing ash seedlings and whips. The native tree is virtually a weed in many places and must be one of the easiest trees to propagate. The government should have introduced bio-security to the standards of Australia and New Zealand, decades ago. In recent years we have imported Phytophthora ramorum which originally affected rhododendron and viburnum but which subsequently seems to have mutated to cause sudden oak death, and to attack larch plantations.

This gives me the excuse to ask if we should be re-introducing butterfly species from foreign stock? How do we know that they are pathogen free? I suppose the same risk occurs because of natural migration of the insects, or do our "extinct" butterflies not arrive in this country in anything like the same numbers as a re-introduction?

JohnR wrote:...This gives me the excuse to ask if we should be re-introducing butterfly species from foreign stock? How do we know that they are pathogen free? I suppose the same risk occurs because of natural migration of the insects, or do our "extinct" butterflies not arrive in this country in anything like the same numbers as a re-introduction?

Reintroductions using foreign stock are only ever likely to be carried out for species extinct in this country, in which case they require a DEFRA license. I think this requires some pretty extensive screening for pathogens of the stock being used - this certainly happened with the recent release of the bumblebee Bombus subterraneus at Dungeness. Most butterfly releases would require the rearing of stock through several phases of their lifecycle, which I would have thought would make accidental introduction of pathogens rather harder than with bumblebees which are both obtained and released as adults.

The law regarding releasing alien animals is far stricter than with plants. I myself have released numerous alien plants of unknown provenance into the wild...it is called gardening...

Seems that moths will suffer the biggest direct 'hit', but the widespread destruction of our third commonest native tree is bound to have serious repercussions for butterflies as well as other forms of wildlife.