Sunday, 27 November 2011

Spot of bad luck

I took a quick spin round Drumboe woods and found a few things worth noting.

This is a good time of year to find mines of Ectoedemia sp. micromoths in 'green islands' in fallen Oak leaves: the leaves you want are quite easy to identify due to the green part contrasting with the brown of the fallen leaves. These micromoth larvae extend their feeding season by blocking off the chlorophyll return valves in the leaf. This ensures that a supply of food continues to be available even after the leaves have fallen from the tree. The specimen shown below had a bit of bad luck, however:

Ectoedemia micromoth mine in 'green island' in Oak leaf
The mine starts at point A (near the midrib and on a sub-vein of the leaf) and follows the sub-vein for a while before beginning its blotch mine at point B. This is all normal procedure and has so far worked well for the larva. Unfortunately, the point chosen for the blotch happens to be exactly at a place where the valve-closing has failed, and the chlorophyll is gone, making that part of the leaf useless as food. The mine has been aborted at this point, probably because the larva has starved. Leaf-miners follow some fairly complex rules when making their mines to help ensure that:

  • they don't fall out of the leaf
  • they end up at a part of the leaf that contains enough food for their growth and development
  • the mines don't cross themselves, which would force them to encounter (and eat) their own dung

Some of the rules involve following veins, others force a change of direction after a certain amount of time; other decisions are made by the female when she lays the egg. The rules don't always work, but I find that the vast majority of mines are successfully completed. I'm guessing that in this case the rule to turn away from the sub-vein is timed and the location was just plain unlucky.

You can see a normal mine here:

I found a few fungi including this Clitocybe vibecena:

Clitocybe vibecena
And a very gone-over Scleroderma citrinum earthball, resembling nothing so much as a piece of orange-peel:

Scleroderma citrinum earthball
Earth-balls disperse their spores by breaking down the outer surface, enabling the spores to be wind-distributed. The outer crust of the fungus is conveniently structured with fragile fissures which make this break-down much easier.

Even dead and now-useless parts of plants can have innate beauty: this empty seedhead of Hogweed was worth photographing:

Hogweed seedhead

Sycamore leaves are covered in their tar-spot fungus Rhytisma acerinum:

Sycamore tar-spot fungus, Rhytisma acerinum
As usual, this fungus is spread by wind-born spores. Notice that most fungi try their hardest to maximise the area available for spore production: the surface of the fungus is wrinkled and domed.

We have had solid rain for the last two weeks and I haven't seen a single moth in that time. The last night, in pouring rain, a single specimen of Red Sword-grass came to light. The Red Sword-grass hibernates as an adult, so something must have stirred this one from its hiding place.

Red Sword-grass
 Red Sword-grass has a mostly western and northern distribution and is found mostly near bogs or heaths.


Toffeeapple said...

You are a veritable mine of information Stuart, thank you.

Gill said...

That leaf-miner info is absolutely fascinating.

I guess the poor moth was avoiding drowning....

Gill said...

I was watching a programme on TV last night, and they said that slime moulds were a single-celled organism - which tallies with the amoeba relationship but is hard to believe when you see and watch them.

There also seem to be different types, from the creeping "dog-sick" ones on grass to those that look - and feel - just like pink marshmallows on logs (Lycogala sp.). Extraordinary.

Stuart said...

@Toffeeapple:"You are a veritable mine of information". Good pun......;)

@Gill: I was initially sceptical that slime moulds could move. I tended to interpret the apparent movement as consecutive generations of new specimens leaving a trail of corpses behind them. But I came across a 'specimen' (actually a community) that had formed and then made a bee-line for a mushroom some 15 cm distant. Unfortunately, the photographs didn't work (too dark). I read somewhere that colonies of slime moulds are being tested for use as light detectors in robots .