www.ukbutterflies.co.uk

This was in "The Times" 29th March 2008. Sounds ominous.

http://www.timesonline.co.uk/tol/news/e ... 642889.ece

Jack

At least that nonsense in the Times about the larvae eating eggs of the predatory fly was corrected by Liz Goodyear on BBC TV this morning.

Of course the Tortoiseshell larvae are "stung" in the usual way. I have bred Torties in the past and a high proportion of larvae collected in the wild were parasitised. Is this a species of parasite new to Britain? (Sturmia bella)

Jack

Just found the answer to my own question:

"Sturmia bella, a very recent addition to the UK list (see New Tachinids page) but has been surfacing in quite a few surveys in 2000 and 2001. This fly has colonised rapidly and is likely to occur anywhere in Southern England - its hosts appear to be the larvae of species of medium to large butterfly of the orders Nymphalidae & Satyridae"

So might this be the reason for the decline of the Wall Brown?

A major question that has to be asked is does Sturmia bella attack insects other than lepidoptera? It would seem from that quote that they do not. Then I presume we can anticipate cyclical fluctuations of Nymphalidae & Satyridae butterfly populations (cf Holly Blue and its parasites)

Jack

I have seen more Small Torts this spring than any spring for the past several years. Today (15th) for example, I saw three spiralling together.

This Sturmia bella parasite is clearly a new threat but certainly over the past 17 years or so that I have lived in South Cambs, ST numbers have fluctuated enormously from being very numerous to very scarce indeed. I had always assumed the fluctuation was parasite related and it could well be that the cyclical abundance will simply continue as before, even with the arrival of Sturmia bella. So far, 2008 seems to be promising to be a good year.

Jack

Three Small Tortoiseshells were seen by the person walking the transect at Magdalen Hill Down Extension today. She said it was the most she had seen together for years. Odd ones had been seen a few weeks back by our warden Patrick Fleet