One of the tiniest moths I’ve ever seen

I was tidying up the mothing equipment, which is basically a box and egg cartons when I noticed a Least Carpet roosting on a window frame in the conservatory, I stepped up with a pot to catch it so I could release it into the back garden but spotted another tiny moth next to it. At this point, I wasn’t even sure it was a moth. It looked orange with what seemed to be white stripes. I grabbed a quick phone macro shot, before potting it.

It wasn’t a species I’d noticed or recorded before, but the ObsIdentify app ticked it as the Horse-chestnut Leafminer, Cameraria ohridella. This was confirmed by a quick look at the species page on UK Moths. LabLit on twitter has now told me that the moth’s species name “ohridella” is named for Lake Ohrid in Macedonia.

I set up my macro “studio” and got some closeups of the moth against a matte white background, once it would sit still for more than a second or two. The moth is a mere 4 millimetres, I’d say, thank goodness for macro lenses and extension tubes.

As the moth’s name would suggest, the tiny larvae of this moth species, grow inside leaves of the Horse Chestnut tree, nibbling their way around the interior of the leaf and forming what are referred to as leaf mines. An infestation of this moth can ravage a tree leaving its leaves brown and withered at the end of summer and giving the appearance of imminent death in the tree. Thankfully, the damage done by the leafminers, while more than cosmetic, does not seem to harm the Horse Chestnuts. They lose their leaves in the autumn, as all deciduous trees are wont to do. Incidentally, the UK Moths site points out that a fungal infection has a similar effect on the appearance of the leaves of this tree.

The moth species was first recorded in Macedonia in 1985 and took just 15 or 16 years to reach the UK. It was recorded in Wimbledon in 2002 but was abundant so may have arrived just after the eponymous tennis tournament the year before. First seen in my village of Cottenham in 2004 and recorded by a fellow mothing friend at the other end of the village in 2022. I may well have seen it last year without realising, of course.

UPDATE: 27 July 2023, we camped under a Horse Chestnut at Cherry Hinton Hall for the Cambridge Folk Festival. The tree was covered in larvae and lots of adults flying about.