Tuesday, 13 October 2009

Smart Miners

Leaf miners on deciduous trees have a limited season for their development: they need to feed while leaves are green. That means they are usually only found between April and September/October. In autumn, trees withdraw the chlorophyll from the leaves for reuse in the next next year, turning them brown before they drop to the ground to become composted.

Some of the Ectoedemia micromoths have found a way to block the return valves, creating small 'islands' of chlorophyll in the leaves, even after they have fallen, thereby extending the length of their season. This Oak leaf has a couple of 'islands' containing mines of Ectoedemia heringi:


Bright, white mines with widely dispersed frass (dung) are usually dipterous. These are the mines of at least 14 specimens of Phytomyza spondylii on Hogweed.

Notice the crescent-shaped exit holes where the larva has left the leaf to pupate:


Another new miner for me: the micromoth Caloptilia syringella on Ash. I suspect this one is usually too high in the tree for me to see it, but this branch had broken in high wind.


A couple of moss shots. The capsules of Thuidium tamariscinum:


And a shot of Hookeria lucens, showing how the overlapping leaves retain water: one of a few techniques used by mosses to keep wet.

3 comments:

Gill said...

"Some of the Ectoedemia micromoths have found a way to block the return valves" Fascinating. I wonder how this works? It presumably also means that when the leaf is still on the tree the chlorophyll in that patch produces food (sugars etc.) thata dannot make their way back to th tree, but are available for the larva to eat; clever.

Anonymous said...

Did you rear the adult as Phytomyza pastinacae makes identical mines?

stuart dunlop said...

@ Anonymous (or should I call you Mr. S?) Phytomyza pastinacae isn't on the Irish list. The general rule we apply across wildlife groups in Ireland is that unless a specimen of a GB confusion species is proven to exist in Ireland, then we continue to record the existing known species. This explains my previous comment on another forum.