I don’t find many leafmines on Aspen, probably because there aren’t a lot of Aspen trees growing locally. Also, I haven’t been finding many mines made by creatures other than moths but today’s find is an exception, as these silvery meandering gallery mines on Aspen leaves were made by the larva of the tiny fly Aulagromyza tremulae.

If I hadn’t been doing a spot of leaf-turning, I could easily have missed these mines, as they are almost exclusively made in the lower surface of the leaf (see images below showing the lower and upper leaf surfaces). This is one of the characteristics that distinguishes these mines from those of other species, though Barry Warrington, who runs the National Agromyzidae Recording Scheme and website, discovered this wasn’t always the case when he recently bred Aulagromyza tremulae flies from upper surface mines. (Barry has confirmed the identity of the mines pictured here, fortunately.)

This little fly has two broods per year, so mines can be found on Aspen (Populus tremula), and also on Black poplar (Populus nigra), in the early summer and again in early autumn. I haven’t managed to find any images of the adult fly so maybe I should try to breed one through to see what they look like. If that happens, there’ll definitely be a show-and-tell post.