Tuesday 8 October 2013

Half moon highlight

Chris Durdin, NWT Thorpe Marshes

caddisfly Limnephilus flavicornis

 One of the challenges of recording wildlife at NWT Thorpe Marshes is that the penny has dropped that I know rather little about a lot of wildlife, especially invertebrates.

Happily, help is on hand with the NWT’s Wildlife Information Service. It helped me last October when on one our monthly guided walks there were hundreds of brown insects flying around, especially on the edge of the gravel pit, St Andrew’s Broad. I worked out that they were caddis flies. In response to a photo, I learned they were probably
Limnephilus flavicornis, known by anglers as 'cinnamon sedges'.

Most of us have heard about the extraordinary underwater cases of caddis fly larvae: using sticks or stones to protect themselves from predators. Seeing them is a different matter.

The synchronised emergence of adult caddis flies is one opportunity, a literally short-lived phenomenon when the adults mate, lay eggs in the water or overhanging vegetation, and die. Looking again at my photos, I see they lack the proboscis of a moth: most adults don’t feed.

Well, it happened again last Sunday, 6 October. Dozens of what looked like brown moths were fluttering clumsily around, landing on rushes and other vegetation.

Limnephilus lunatus
This time, having looked carefully at a photo, I am suggesting an ID without the help of the Trust’s expert. I think it is the rather similar Limnephilus lunatus – the lunatus specific name coming from the half-moon shape at the end of the wing. But I’m happy to hear from any NWT blog readers who know better!

For help with identification, you can email photos to wild@norfolkwildlifetrust.org.uk

More wildlife news from NWT Thorpe Marshes and details of monthly walks on http://www.honeyguide.co.uk/thorpemarshes.htm

Chris Durdin

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