Purple emperor - first the good news then the bad

I was doing a bit gardening last week (shock horror probe I hear you say) and I forgot to mention an interesting discovery. A dead Purple Emperor butterfly was lying in amongst the sedums near my Rambling Rector's trellis, being dispatched by some very purposeful ants. I was sorry to see the thing was dead but glad to think that once it had flown in my garden. If I'd been outside gardening a bit more I might have seen it.

I don't think I have ever seen one of these butterflies before (apart maybe when I was a child I think someone pointed one out to me once), but they are one of the sights I am always hoping for (along with a kingfisher by the river, or an owl at night).

For the interested, it has the latin name Apatura iris. I think the common names of butterflies and moths are fascinating and often poetic - sometimes their scientific names too. But what do they mean? It would be interesting to have a book explaining the scientific names of our natural history - I think I have seen one for garden plants. I will investigate and report back.