A mystery solved

At low tide we took a walk along the beach to see the seal haul out. 
We were perplexed by strange tracks that we found in the sand.  About half an inch wide they continued along the beach for many metres in quite straight lines. Improbable theories were proposed before we came across the real cause, which you can see in the "extra". They were the tracks of Woolly Bears!
For some unknown reason woolly bears, the over-wintered caterpillars of the Garden Tiger moth Arctia caja, were descending from the vegetated dunes down onto the bare sand of the beach and heading off in straight line. Why, I don't have the faintest idea, but I think that our African friends were impressed!
I have back-blipped the entries for the last 3 days, starting here.