Saturday, 19 April 2014

Extra high pressure

A second consecutive day of blue sky was a bit unexpected: the forecast was cloudy with showers! I think I remember that in the olden days (pre-warming) we could rely on weather forecasts for about a week ahead. Nowadays, it seems they can't even get it right for the next 24 hours. I rather suspect the computer models that they use to make forecasts no longer work now that we have warming.

Still, making hay.....

I went down to the local river, where Wild Garlic and Bluebells make the first appearance. A few heads of garlic were in evidence:

Flowers of Wild Garlic - Allium ursinum

And a single Bluebell plant had started to open:

Bluebell flowers just opening
 I also caught a few shots of hoverflies. First of the smaller species is usually Melanostoma scalare:

The hoverfly Melanostoma scalare (male)
I always think that if you were hoverfly-sized, then a flower must be a wonderful place to explore, rest and feed.

Syrphus hoverfly species are a little bit earlier this year:

Syrphus sp. hoverfly (female)

There were a great many craneflies in the air. This female (long, pointed abdomen) stopped long enough for a shot:

Female Cranefly

The larvae of craneflies are the 'leatherjackets' that eat the roots of grasses and make empty patches on lawns.

As I'm writing this, we appear to be heading for a third consecutive day of blue sky, so I'm off out again.

Wednesday, 16 April 2014

Beautiful high pressure

A rare high-pressure weather system brought dry heat yesterday, so a lot was going on.

My first worker bumblebee (probably Bombus terrestris, but hard to be certain) of the year was gathering pollen from a half-open Dandelion:

Worker Bumblebee with phoretic mites
When I got back to the computer, I spotted the mass of mites on her back, between the wings. Phoretic mites attach themselves to a number of different insects, but do not feed on them directly: they use the insects as transport between feeding locations, such as bee nests or corpses.

I previously showed mites on this page:

Notice that they attach themselves in a place where the transporting insect cannot easily wipe them off, and can also choose precise locations that disguise their presence.

Field Horsetail has pale fertile shoots which precede the green sterile ones:

Fertile shoot of Field Horsetail
The cone at the top produces spores which have 4 curved 'legs' that are very responsive to humidity. As the air humidity changes, the legs expand and contract, curling and uncurling. Little hooks at the end catch on to surrounding vegetation, and the spores pull themselves around in different directions order to increase their chances of dispersal. Here's a shot of the spores that I took in 2003:

Equisetum spores at x100
As an aside, I noticed that Google Chrome has a facility to search for 'similar pictures'. The list of images for this included Chinese script, pen and ink portraits and maps.

Bilberry (local name mulberry) flowers opened over the last day or two:

Bilberry flowers
Leaves have scarcely emerged before their fungal rusts appear. This is the rust Puccinia chaerophylii on Cow Parsley:

Puccinia chaerophylli on Cow Parsley 

Sunday, 6 April 2014

Flat to the mat

Everything is now progressing at full speed: I saw the first House Martins last week and Swallows will be around in the next day or two.

A few trees are in leaf, with Willow leading the way as usual:

Willow leaves

Hawthorn wasn't far behind, and hedges are now greening up very nicely:

Hawthorn leaves
Notice that the leaves are all in pristine condition. That won't last long once the caterpillars and leaf-miners wake up and start feeding. This synchronisation between insect and foodplant is very well illustrated by the Beech leaf-miner Orchestes fagi: the instant the Beech leaves unfurl, the female weevil lays her eggs on the central vein of the leaf and the miner starts to tunnel towards the leaf margin. A few days later, the mine is complete and the next generation flies off to start the cycle all over again. The synchronisation in this association between two species is critical, since the leaf is only soft enough to eat for the first few days after opening: after that it's too tough. Keep an eye on Beech trees towards the end of the month and you should see the mines within a couple of days of the leaves appearing.

A few flowering plants are now producing flowers more or less all year round and are in flower alongside the spring-flowering species. I suppose we are now warm enough for hardy species to keep going through milder winters. This specimen of Red Dead-nettle has survived the few cold nights and has plenty of flowers already:

Red Dead-nettle
Other flowers that have survived continuously include Herb Robert, Sowthistle, Smooth Hawksbeard, Dandelion, Daisy and Bush Vetch. All of these are currently in flower here.
Other species are showing when conditions are right. This specimen of Dark-lipped Banded Snail is one of many colour variants of this common species:

Dark-lipped Banded Snail
I'll show other variants as and when they appear.

I'm always intrigued by the intense colours that can sometimes appear and then seemingly vanish without trace. This Daisy has an intense purple pigment to the tips of the petals, but the fully open flower will be more or less pure white:

Daisy bud, showing the purple petal tips
I suppose there is a fixed amount of pigment that is eventually shared over a larger area. Some fungi show exactly the same effect, getting paler as they mature.

Tuesday, 1 April 2014

More sun: more flowers

Yesterday was bright and warm, so the spring flowers responded appropriately. Wood Sorrel appeared during the day:

Wood Sorrel
And Barren Strawberry started to open just as the sun was going down. It opened fully today in hazy sun:

Barren Strawberry
Barren Strawberry can be separated from the Wild Strawberry by the little notches in the outside of the petals, plus the bluish cast to the leaves, and the fact that the final tooth in each leaf is shorter than its neighbours:

Leaf of Barren Strawberry
During a school foray today, one of the students called me over to look at some slugs and snails that she had found. It was clear to me that I had never seen some of them before. It turns out that the large slug is the Irish Yellow Slug - Limacus maculatus - which was originally thought to be endemic to Ireland, but it originated from the Crimea, spreading from Ireland to England only late in the 20th century:

Limacus maculatus (right) and Oxychilus cellarius (left)
The small snail to the left is the Cellar Snail - Oxychilus cellarius. Both new to my Species List.