When we were walking along Whitburn beach in Sunderland this afternoon I noticed a dense flock of about 150 black-headed gulls on the tide line and as we got closer I could see ....
A closer look revealed many thousands of these tiny white maggots washed in by the incoming tide.
Here they are - the larvae of the seaweed fly Coelopa frigida.
About a week ago we had a spell of warm weather that must have been perfect for these flies to breed in the big piles of kelps and wracks that form natural compost heaps on the beach.
Then two days ago Storm Doris arrived, creating mountainous waves that would have washed the rotting kelps and the fly larvae into the sea.
Today the tide brought them back in again in enormous numbers on this short stretch of beach, providing a fantastic feeding opportunity for the gulls and also for waders like turnstones, sanderlings and redshanks.
As the old saying goes, 'it's an ill wind that blows nobody any good'.