Stitchwort

Yesterday Nyctalus posted some fine pictures of Durham University's magnificent bluebell wood. Here's a picture, also taken yesterday, of another of the same university's woodlands near its North American arboretum. Here the ground flora is dominated by a carpet of greater stitchwort, enlivened by a sprinking of bluebells.

Stitchwort flowers are carried on a very slender stalk, who when the wind blows through the woodland it sends a 'shiver' through the flowers.

St. Mark's Fly

St. Mark's fly Bibio marci gets its common name from the belief that it always emerges on St. Mark's Day April 25th., which isn't too wide of the mark because swarms of these flies have emerged over the last few days.

They usually hover up and down just above the grass but in this morning's overcast weather literally thousands were resting on the sycamore leaves on the edge of a woodland just south of Durham city.

These flies have remarkable eyes - four in males, which you can read about here and you can find an interesting post by Nyctalus on these common insects, showing one in flight, here.

Out of the Blue...

There we were, high on the moors between Wolsingham and Hamsterley, when we heard the distant clamour of geese ........... then these two greylags hove into view ......

..... passed a few feet overhead with a lot of excited 'honking' and then disappeared over the horizon.

Sand Martin colony

The soft banks of the River Tyne upstream of Corbridge in Northumberland provide excellent nest sites for sand martins.

New burrows are ususally dug by males each year and last weekend they were introducing their mates to their nesting quarters.

At this stage there's a lot of excited activity, with aerial chases followed by settling in the mouth of the nest tunnels, then sudden panics where they all take to the air ...

... before down settling again

Spring Wild Flowers in Weardale

Last autumn I posted some pictures of a walk up through Slitt Woods in Weardale, following the course of Middlehope Burn upstream. These pictures were taken this weekend, following the same route, starting with masses of sloe blossom in the woodland, attracting the attention of this green-veined white butterfly.

All through the woodland there's a fine display of primroses and around the hazels ...

.....these flowers of toothwort, which is a parasite on hazel roots, are in bloom.

The mountain pansies are just coming into flower in the grassland on the moorland edge. There are numerous colour variations.

Sedges thrive in the short, sheep-grazed turf. The yellow 'paintbrush' is the male flower, composed of numerous stamens, and the white feathery stigmas of the female flowers can be see further down the stem

The ruins of the old lead mine buildings form a natural rock garden for dog violets. 

Field woodrush, growing in the short turf.

The early purple orchids at the top of the woodland are earlier than ever this year, thanks to the warm, dry weather.

Marsh marigold thrives around the old lead washing floors, where lead was separated from crushed rock using the force of flowing water. The parabolic flowers of marsh marigold focus the sun's rays and the temperature inside the flower is always a few degrees higher than outside, making them a popular resting place for sun-basking flies.

Up in the edge of the high pastures cowslips are in bloom.

Wolf Spiders

This is a male wolf spider - a Pardosa species, I think, though I'm not certain which one but it could well be P. amentata. It's spring, he's looking for a mate and success depends on being very cautious and on using those two palps - the black, hairy, club-shaped arms on either side of his jaws - with consummate skill. If he gets it right he'll become a father, if he gets it wrong he might well become a meal because....

... this is the object of his affections. The female is over twice his size and very aggressive. Wolf spiders chase down and leap on their prey instead of snaring it in a web and have (for a spider) good eyesight. She's watching his every move, so ......

.... he creeps very cautiously over the edge of her leaf and tentatively waves his left palp. Every now and then he'll vibrate it and the tremors will travel through the leaf and be picked up by her feet.

He creeps a little closer and waves his left palp again, like a sailor waving a semaphore flag .....

... then closer still and waves the right one. It's a courtship that goes on for a long time, and if it's successful the outcome looks like this....

Oystercatchers and Swallows

One of the characteristic bird sounds out on the moorlands of Weardale at this time of year comes from oystercatchers that arrive here from the coast to breed. When we were out at Middlehope burn yesterday their calls echoed around the hillside ....

... and we watched several of these noisy courtship chases.

The swallows were back too. Every year at least one pair nest just inside the entrance to this mine level (below) - the tunnel that provided access to the lead veins that were once the source of the mineral wealth of this valley.

The mine tunnel entrance is sealed off for safety but the swallows ...

..... hurtle towards the bars, chattering as though they are excited to be back in this bleak moorland landscape after spending the winter in Africa. 

Here's one coming out of the mine entrance, after checking the state of last year's nest inside. They fly towards the gaps between those iron bars with unabated speed and must have to time their wing up- or down-stroke with incredible precision to ensure that they don't break a wing on the iron grill.

It's a Hard Life being a Miner

Tawny mining bees often visit our garden, sometimes feeding on the gooseberry flowers in spring, but I've never managed to find evidence of their nests here. But they must nest somewhere fairly close, because we also receive regular visits from two of their parasites.

Bee-flies lay their eggs near tawny mining bee nests and their larvae crawl down into the underground nest chamber, eat their host's grub and monopolise the store of pollen that the bee lays down for it. Bee-flies are relentlessly active, which means it's almost as difficult to photograph one at rest as one in flight. But this one paused just long enough on the fence to have its photo taken, displaying its furry bee-mimic body and long straight proboscis, used for sucking nectar from deep within flowers.

And this is another enemy of the tawny mining bee, feeding on our forget-me-nots. It's a cuckoo bee (Nomada sp.) - a solitary bee that also behaves like a cuckoo, laying its eggs in bee-fly nest holes where its larva steals its host's pollen supply. Notice that it has few body hairs and no pollen combs and baskets on its legs for collecting pollen to feed its offspring; that's done by the unfortunate tawny mining bee.

Green Dock Leaf Beetles

I found scores of these green dock leaf beetles Gastrophysa viridula mating on dock leaves in the pastures beside the River Towy near Carmarthen earlier this week. The larvae chew holes on the dock leaves then pupate in the soil. In a good year they can produce three generations.

The beetles have beautifully iridescent exoskeletons which change from metallic green to bronze depending on the angle of the light. A single female can lay up to 1000 eggs. For the males, finding a female to mate with is highly competitive. In the top picture you can see two males confronting one another over a female.....

... and in this picture you can see a startling case of coitus interruptus, where a mating male - still coupled to the female - has been dragged off her by a rival. I thought this sort of thing only went on in the Bigg Market in Newcastle on a Friday night.....

Room to Grow

Unless they're deliberately cultivated in an arboretum, most trees never get the chance to spread their limbs and assume their natural shape throughout their life - all too often they're confined to hedges and hacked about during hedge trimming or struggle to compete for light and space in a woodland. But this ancient wild cherry has been given room to grow. For some unknown reason it was planted (or maybe accidentally sown by a bird) in the centre of a field near Harperley in County Durham. Here it is in in magnificnet isolation, in the snow-covered landscape last winter........

........ and here it is today, photographed from exactly the same spot, covered in blossom and with a few sheep enjoying its shade on an unusually hot April day.

Ghostly Midges

So there I was, on Monday evening, leaning over this bridge over the River Towy at Nantgaredig near Carmarthen in south Wales, watching the sun set, when I was enveloped in a massive swarm of midges. So, just out of curiosity, I set my pocket camera to its macro setting, turned on the flash and held it skywards into the swarm .........

........... and this is what I got. The midges that are in the plane of focus are vastly over-exposed so appear as ghostly white silhouettes but if you double click to enlarge the image you can see the structure of some of them quite clearly. They fly with their legs outstreched.

If you enlarge this image you can see more of the midges that were too far away to be illuminated by the weak flash. They appear as black dots above the 'ghosts'.

I think they are non-biting midges Chironomus sp. The males dance in these large swarms and grab females that fly in, mating in mid-air.

Yellowhammer

Colours straight out of a child's paintbox - blue sky, fresh green hawthorn foliage and a sulphur-yellow yellowhammer.

The hedgerows around here are full of their wheezy song at the moment.

Click here to listen to the song

A Tree-Spotter's Guide to Flowers: 4

Field maple Acer campestre flowers are produced at the same time as the leaves in Spring, like sycamore but unlike Norway maple that opens its flower buds before the leaves expand. They point upwards, unlike sycamore flowers that dangle.

Unlike those other two Acer species, the green petals of the flowers are covered with long hairs. Field maple also produces a lot of nectar (you can see the drops glistening here, especially if you double-click on the image to enlarge) and this attracts small flies that pollinate the flowers. There are eight stamens and a stigma that's divided into two branches.

Oak catkins are produced at the same time as the leaves expand in April. These are male catkins that will release pollen - the female ones that will produce acorns are much shorter, with just a few florets.

Sweet chestnut in full flower, showing the long male catkins. These are produced well after the leaves have fully expanded, in July. This means there's not much time before autumn for the fruits to develop - which is why we never get much of a crop here in North East England unless we get a long, mild autumn.

The stamens on the make catkin of sweet chestnut. The male flowers have a sickly smell.

 

Limes (Tilia spp.) are relatively late bloomers too, opening right at the end of June. They dangle from long stalks that have a single elongated wing attached, that later slows the fall of the seeds and aids their dispersal. Lime flowers produce large amounts of nectar and if you stand underneath a tree when it's in full bloom it literally hums with bumblebees, that find it irresistible.

For more information about trees click here.