New Moth for the Patch

With the moth tally for the patch standing at a whopping 21 species, it was always a pretty safe bet that I would soon find an additional species or two. However, the one I found yesterday was not entirely expected. 

I was wandering the grounds in a rare bit of glorious sunshine, sticking my face into hitherto unexplored cracks and crevices, when I found myself looking at a small plant of Black Spleenwort hanging out of a rock face. Immediately obvious were the numerous brown patches across the frond. These struck me as being localised feeding signs rather than diseased or damaged areas, so I moved in for a closer examination. Sure enough, I soon spotted a tell-tale 'pile of debris' on the underside of one pinnule. I plucked the frond and popped it into a pot for closer scrutiny once back indoors. 

Note the brown patches, these are the feeding signs of a certain micro-moth

I was fairly confident that this was the work of a Psychoides moth, of which there are two species in Britain. A quick check of the caterpillar itself would tell me which of the two I had here. One has a black head, followed by a black prothoracic plate and has a black plate at the rear end too. The other has a pale brown head, a transparent prothoracic plate and lacks any black at the rear end. Time to haul it out of its silken retreat and have a look...

The middle image shows the silken retreat which I opened up to reveal the larva within

So I see a caterpillar with a pale brown head, a transparent prothoracic plate (the shield that covers the rear half of the head) and no dark mark at the rear end. My moth is Psychoides filicivora, which is the only one of the pair so far known to occur on Skye.

And just to clarify, here's an image of the two species side by side (courtesy of Wikipedia)

I found this species new to Skye several years back, and it's one that I still happen across from time to time although I wouldn't say it's particularly easy to find. However it can be numerous where it does occur, particularly when the hostplant is Hart's-tongue, which has fronds large enough to hold several larvae each. It also occurs on Polypodium, but I think this could be the first time I've found it feeding on Black Spleenwort. 

As far as I can tell, there isn't any Hart's-tongue growing on site. If there is it must be a random plant or two hidden away in the undergrowth. There are two discrete areas with polypodies growing on the rocks, and a mere handful of further Black Spleenwort plants, so I'm actually quite surprised the moth is here at all. Unless it's utilising Dryopteris ferns as the main hostplant? I'll have to investigate that further. I don't tend to check Dryopteris for these moths, which might be something of an oversight on my part. There are certainly plenty growing around the hotel grounds. 

Today I stood in the car park and slowly scanned a hillside just across the loch. One Buzzard, one adult White-tailed Eagle, a Raven and one subadult Golden Eagle. Not too shabby a scan. Oh, and best of all, I found a patch of Sheep's Sorrel at the end of the path. Winner!