Harry Rutherford reports
The moth season is tailing off now; I might get 15 species on a mild night in October, compared to 60 or 70 in June or July. It never completely stops, though. Just like butterflies, many species overwinter as adults, and will emerge from hibernation if the weather is unusually warm. But there are also some true winter specialists, like Winter Moth, November Moth and December Moth.
Still, this seems like a good moment for a yearly round up. The headline is that, in my second year running a moth trap, the new species kept on coming. I ended 2016 with my garden list on 301 (plus a few that I can’t identify without dissecting them). I’ve done slightly better this year, with 343 species so far; partially that’s because I started earlier in the year and added some spring moths to the list. 98 were new, taking the garden total to 399.
The most exciting moment was in March, when I caught a small moth that didn’t quite look like any of the pictures, until I was browsing on a German moth website and found it was a good match for Caloptilia honoratella, a Macedonian species. Which obviously seemed unlikely, but further googling revealed it has been spreading recently, and has been added to the German, Italian, Spanish and French lists in the past ten years, and was confirmed in the Netherlands just last year. So I had a potential new species for the UK… but unfortunately I only had a photograph, and given its rarity, the county moth recorder wasn’t willing to accept the record without an actual specimen. Which was a bit disappointing, but what I expected, really. It’s a pity not to be able to claim it, but if it is spreading into the UK, sooner or later more will turn up and it will be vindication of a sort.
Another notable arrival was the notorious Box Tree Moth, whose caterpillars wreak havoc on box hedges. It’s an Asian species which has only become well established in London in the past three years; last year I had none, this year I’ve caught 98 of them, as well as finding the caterpillars in the garden.
This year, as well as the adult moths I have started recording leaf-mines. The most visible example of leaf-miners around Dulwich are the Horse Chestnut Leaf-miners, whose caterpillars live inside the leaves of horse chestnuts and leave them covered in brown blotches. The moths are only a few millimetres long, but present in staggering numbers — I had 390 in the trap one night this year.
There are lots of other leaf miners, though, and many of them can be identified by a combination of the host plant and the shape of the mine. Admittedly, leaf-mines are a pretty nerdy hobby, even compared to moth-trapping; but it has the basic pleasure of listing, plus an element of detective work, and it gives you an extra something to look for when you’re out walking. I’ve recorded 49 species as leaf mines so far, including for example 15 species in Brockwell Park, 7 in Belair Park, and so on.
At some point the new species will be arriving much less frequently, and I don’t know whether I will still be motivated to drag myself out of bed early in the morning when that happens. But there were still lots this year, and there are still plenty of common species I haven’t recorded. So it will be interesting to see what 2018 is like.