Mothers' meeting

A most extraordinary phenomenon has been discovered just up the canal from here by a fellow moth-enthusiast, Jon Carr, when he was out paddle-boarding. Passing under a low bridge, he took a closer look at a couple of outcrops of what superficially appears to be fungus attached to the gloomy stonework. He did well to spot them; walking or cycling by, I would never have given them a second glance.

And lo and behold! They are clusters of roosting Old Lady moths, a large but somehow tatty and forlorn-looking species, even when freshly hatched. Here's one I spotted eight years ago in what looks like a swimming pool - and certainly not like the waters of the Oxford Canal - though actually it's the bonnet of our car where the moth was having a warm doze.

Back to our clusters. What are they doing, Jon asks on the Upper Thames Moths blog where he reported the discovery yesterday?

What indeed. The mothmeister Dave Wilton speculates that they may be seeking a gloomy refuge in the generally warm weather. The moth is a species known for skulking in garden sheds and other cool, dark places. Another moth expert, Tom Stevenson, commented on the UTB blog that he'd seen similar numbers last year underneath a road bridge. Here's the smaller of the two roosts, both of which make use of cracks between the stones.

Why are they unmolested by the spiders which also frequent the arch? And how long do they intend to stay? The bridge is only a ten minute bike ride from here, so I wobbled up along the towpath this morning and - after nearly losing my specs when their case shot out of my shorts pocket, got the photos here.

They are marginally clearer than Jon's - he was both in the gloom and on a paddleboard - but, as you can see, the iPhone has big problems with the extreme lack of light and I need to do better. All being well - because we have our younger son bringing pals for a birthday fiesta here this weekend - I will take a torch and other suitable equipment in our dinghy Dolores, Empress of Thrupp on her first-ever moth exploration expedition.

Thanks meanwhile to the two narrowboats from Hull and Northampton which kindly allowed me to step aboard and take the pics here (and to the hireboat Balliol which patiently waited during the exercise). As almost always with interesting wildlife, the moths have chosen the hardest possible place for an interested human to reach, on the furthest point away from the towpath.