Sunday, 30 March 2008

Moths and leaves

I was up in the deforested heath looking at willows for signs of bud-break and spotted this caterpillar on a bush. Turns out it's the Northern Eggar - Lasiocampa quercus f. callunae. Specimen about 3 cm. long:

This is an interesting species (or species complex). The southern populations feed on Oak and have a one-year lifecycle. Northern and western populations feed on heather and willow and have a two-year lifecycle. Populations in the English midlands vary between one year and two year cycles.

I did find a few willows in bud-break:

And also a single specimen of Alder:

And with catkins:

One of the groups I'll be studying closely this year is leaf-miners. I've previously tended to be a bit cavalier in my leaf-miner hunting, but this year I'm going to be more organised, with target species and timescales all planned in advance.

Friday, 21 March 2008

Fly-killing fungus

For a couple of years, I've been tracking the fly-killing fungus Entomophthora muscae. This fascinating fungus invades the reproductive tracts of female flies - especially hoverflies - and eventually kills them. I can find dozens of dead hoverflies within a few square metres of verge or pathway, so it is clearly an important factor in population regulation.

This is a sample I investigated last year:

From that particular sample I put a few freshly-dead specimens on a slide to see if I could get any spores. Today I remembered to check:

The magnification is x 100, and the spores appear to be rather 3-d and surrounded by a membrane of some kind. I wonder if they're sticky.

Anyway, this fungus is quite fascinating in a number of ways:

It gets ingested by the female fly and migrates to her abdomen. It then begins to expand quite rapidly, emerging from between the tergites as a pink mass. The fungus then compels the fly to climb to the highest part of a stem of grass, or a flowerhead. It then forces the fly to open her wings and extend her legs so that the maximum area of her abdomen is exposed to the wind. It then kills her in situ. The fungus rapidly breaks down and spores are released to be carried by the wind. This compulsion to climb is known as 'Summit Disease', and is an amazing ability for a fungus to have developed.

Current theory (due mostly to genetic sequencing) says that each species of fly is killed by a different form of the fungus. So in future, instead of the generic Entomophthora muscae, we might have e.g. Entomophthora scutellae, and so on.

Tuesday, 18 March 2008

More small things

Up in the deforested heath there is a slab of rock about 1m. across. This slab is a continual source of mosses, and I like to watch it at this time of year. This shot shows two of those mosses: in the foreground we have the hair-tipped leaves of Racomitrium lanuginosum, and the species with the elegant ruby-tipped capsules is Ceratodon purpureus.

This is how the Racomitrium looks in a habit shot. Specimen about 5 cm across.

Also on the rock is one of the smaller Polytrichums, Polytrichum juniperinum. These are male specimens, with the antheridia at the centre.

This green rosette might be a bit confusing at first, but once you get your eye in, it shouts 'liverwort'. Specimen about 6 cm. across.

Close-up examination reveals two rows of complex leaves, each doubled back on itself. This is diagnostic liverwort structure, and it turns out to be the very common Diplophyllum albicans. Main shoot about 12mm long.

There are also a few lichens in the area, on an old tree stump. This is Cladonia polydactyla, with tiny red fruitbodies. To the right you can see the Donegal speciality: Cladonia monodactyla (just joking).

And this is also a lichen, believe it or not. Peltigera membranacea, or Rabbit-paw lichen, growing through grass. Specimen about 30 cm. across.

Tuesday, 11 March 2008

More signs of spring

Leaves have appeared on the Elder. The local name for Elder is 'bo-tree' or 'boo-tree', emphasis on the first syllable, the ee very short.

These embryonic shoots of Hartstongue Fern look like tiny hairy animals. In fact, I think that all early stages of ferns look slightly animal-like:

I thought this 'inside shot' of the Lesser Celandine flower looked interesting:

Not a sign of spring, since I can find Tubaria furfuracea throughout much of the year. This is associated with Hawthorn. Cap about 12mm across.

And just to show that new species can be found at any time of the year: The fungal infection Hormotheca robertiani, on Herb Robert:

Said to be common, but I've never seen it before.

Sunday, 9 March 2008

Mosses, lichens and liverworts, oh my!

Original Hedgerow, leg 1, whilst on a film shoot. One of the things I have to do when on these shoots is 'pretend to be taking a photograph'. What better way to pretend than actually taking shots?

This first shot - on a wall - shows a lichen (Cladonia pyxidata, pale green, centre with pink, embryonic fruitbodies), at least three mosses:Bryum capillare (olive-brown rosettes dotted around the image), Homalothecium sericium (silver-tipped shoot, left of centre), and an unidentified specimen with curled leaves (right edge).

This shot shows the liverwort Lunularia cruciata, with its diagnostic moon-shaped gemmae cups, with gemmae (little bundles of cells that develop into new specimens) spilling out.

This could potentially be a very confusing shot. The central 'specimen' is in fact two mosses. The pale grey cushion in the foreground is Grimmia pulvinata, and the capsules and setae at the rear belong to a specimen of Tortula muralis, which is hidden behind the Grimmia.This is a moss: Plagiothecium undulatum. I find it very reminiscent of a minute fern.

This moss forms 'boots' around all the trees and bushes around here: Hypnum cupressiforme.

It was raining, so I got a couple of water-droplet-shots. The large droplet to the left is on the capsule of Bryum capillare, and the smaller droplet to the right is on Tortula muralis.

Here's the Bryum capsule in closeup: