I found a stunning Monarch butterfly in my garden in Middx in June this year (photo attached) and wondered if there was any organisation that kept any kind of log of UK sightings, or if this is far more likely to have escaped from a butterfly house than actually migrated across the Atlantic! (I did email firstname.lastname@example.org but didn't receive any reply...) Thanks.
Thanks for your reply Mike – glad someone else acknowledged that it would have been exciting at the time, even taking into account the info below! I contacted London Wildlife Trust, as suggested, and this is their reply, in case it's of interest to anyone else:
Thank you for your picture and sighting details of the monarch butterfly earlier this year. Although they do get found in Britain as very rare migrants they are most often found in southwest Britain and nearly always in September and October when they are actually migrating. The date and proximity of a butterfly house to your location would suggest that your individual (which is a male by the way -The black dots on the hind wings indicate this) escaped from there. This has happened before and in one case actually lead to them breeding in 1981. This is also probably why Butterfly Conservation showed no interest in your sighting. As a probable escape it cannot be counted as a wild individual but the London Biological Record Centre called GiGL (Greenspace Information for Greater London) may still be interested in your sighting so the actual address of the sighting location and date would be very useful. In future you can send any sightings in your garden or anywhere else for that matter of birds, insects or any other wild animals or plant you see directly to GiGL by using their website record sheet which can be found here: http://www.gigl.org.uk/submit-records/ You could input your Monarch butterfly sighting directly into this if you wished instead of sending it to me.