A new invasion is coming.

Today's blip was almost yet another variety of Hover-fly. I took several. But I recognised the danger of getting too interested. Before you know it you have joined the British Hover-fly society and bought a £50 book from Princeton University Press on British Hoverflies with over 500 colour illustrations. I have been through it all before.

So a new subject was sought. Here is an alien invasion commonly known as Spartina grass. It arose as a cross between European and American cord grasses in 1870. It was at first thought of as an excellent way of stabilising sand dunes. But it has become an invasive species. Here is a new clump at Sandside on the Kent Estuary. When it gets established it can spread rapidly through creeping rhizomes and dominate whole areas of the shore pushing out other plants and preventing wading birds from feeding.

A few years ago it suddenly took over the Foreshore at Grange over Sands. Residents held crisis meetings and called in experts for advice on how to eradicate it. But the experts said there was no way this could be done. But often after several years it dies back and new grasses take over which create sea washed turf suitable for grazing sheep. Then the river channel changes sides every twenty years and the turf is washed away. Isn't nature fascinating?