Cold weather mothing

Flanders Moss NNR


The moth season has started. Actually, some moths fly through the winter so it never really finishes but just goes quieter. Last Sunday, wrapped up in thermals, waterproofs, woolly hats and gloves etc. we went out to look for moths. Yes, it’s that belly button fluff time of year.


A female Rannoch brindled beauty – belly button fluff.

We were out looking for Rannoch brindled beauties. These are one of Flanders rarest moths – it is  found in less than 30 10 km squares across the UK, and Flanders Moss is one of the most southerly places it is recorded. So, a rare moth and an unusual one. It is unusual because it comes out as an adult early in the year and the females don’t look much like moths: they have no wings and are very fluffy with the fluff  keeping them warm on days such as the one we went out on. The lack of wings is because they don’t need them; they just pump out irresistible chemicals on the breeze that the males detect and can’t help themsleves but to follow the scent up wind to the female. Why fly if you can just sit there and let the males put in the effort?


Male Rannoch brindled beauties – above and below – they have to do all the flying.




The fence posts are also used for egg laying and the orange structure sticking out the back end of this female below is her egg laying tube which she will stick into cracks in the post to deposit eggs.

And this makes them one of the easiest moths to survey. The females climb whatever is nearby to get high so as to give their chemicals the best chance to catch the breeze. A fence post is ideal. So to monitor this moth you just find a fence line in the right habitat and then walk along it, crouched down, counting moths. I am guessing that from a distance it might look a bit strange as you develop a crab like crouch and scuttle with regular pauses but it is scientific monitoring at its best. And you don’t even need to pick good weather as the moths just sit there all through any cold or wet weather waiting for it to warm up and the action to start.

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1 Response to Cold weather mothing

  1. peigimccann says:

    What amazing creatures! It looks as if it helps if the fence post looks like a tree, weathered and covered with lichen!

    Liked by 1 person

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