Monday 14 March 2011

Green shoots of recovery

We've been having some very variable weather for the last couple of weeks, with about 15 cm. of snow at the weekend. The heat last week certainly stimulated some growth on the Raspberry canes:

First Raspberry leaves
I was a bit surprised to see a single flower of Germander Speedwell which has clearly suffered from the sharp dip in temperature that came with the snow:

Germander Speedwell
Leaf-miners always intrigue me, and the most common mine in this area is the micromoth Stigmella aurella. I often pause to have a look at the mine and see if I can work out the factors that determine the route of the mine:
Mine of the micromoth Stigmella aurella 
In this instance, the mine has started below right of centre and looped round a spot of rust on the leaf. It then heads for the central vein (which is the part of the leaf that's furthest away from the edge) and follows that vein for about half the length of the leaf. It then deviates outwards towards the edge (it has to do this at least once, since the central vein isn't long enough for a whole mine) and follows the edge without actually reaching the edge (how do they do that?) before turning back into the central vein to complete the mine.

The large fungal spots on either side of the vein are the fungal rust Phragmidium violaceum, which appears in summer and autumn as bright orange dots inside an expanding purple ring on the leaves.

1 comment:

Out on the prairie said...

Very nice information, I shall be looking at the leafminers more often.