Another day of rushing around allowed me about half an hour at the river in Stratford this morning, searching for dragonflies. It was a warm, sunny day, and there were plenty of insects on the wing, but frustratingly, my only dragon sighting was a brief tail-end view against strong light, and my camera had a melt-down when I attempted to get focus on the shimmering blur. The flight pattern and the perfect X-wing shape said dragonfly, and the size said hawker, but unlike the specimen of which R and I both had a clear view yesterday (that record currently still unverified, and flagged by the automatic data cleaner as unlikely, because of its date), I can’t be sure enough about this one to submit the sighting. Still, I know what I saw: a Migrant Hawker, on 5th November. It has been a remarkable season.
Among the other inverts I saw at the river were several caddisflies, and this one (which was put up from low vegetation by a jogger) obliged me by flying slowly enough for me to track it to rest. I didn’t recognise the markings, but after some research I’ve come down in favour of it being a Brown Sedge (Anabolia nervosa) – a common species, but one I hadn’t seen before. “Nervosa”, contrary to what one might assume, means “robust”, and while I can’t make any comment on its character, it’s certainly quite a big caddis, at about 1.5cm long. Apart from its size, the main identification feature is a pair of small white markings on the forewing, which aren’t too clear here because of the light falling across the wing, but (trust me) are actually present.
The Brown Sedge can be found in both still and running water, and adults generally hatch between July and November. The larvae, which feed on plant litter and other small invertebrates, build protective tube cases for themselves from sand grains, and then stick small twigs to the outside. This prevents Trout from swallowing them – though not, in my experience, Little Grebes, which I’ve seen repeatedly diving for them in the shallows in front of the Water’s Edge Hide at Kemerton.
