Tuesday, June 30, 2015

In the mire

The ruins of the old lead mine workings at the top of Slitt wood, along Middlehope burn at Westgate in Weardale have a lovely flora at this time of year.

Most of the green area that you can see in the photograph above is a mire, full of moisture-loving plants and .....

..... this area, where water constantly trickles out of the mine levels and across the old lead ore washing floor is home to some interesting species. Here are a few that were at their best this morning:

Marsh lousewort Pedicularis palustris, a partial parasite on the roots of grasses.

Ragged robin Lychnis flos-cuculi

Common butterwort Pinguicula vulgaris - for more on this carnivorous plant click here 

Northern marsh orchid Dactylorhiza purpurella

Marsh horsetail Equisetum palustre spore-bearing cone

Sunday, June 28, 2015

Jaws: leafcutter bee

I must that Ryan Clark @RyanClarkNature for helping me with the ID of this male leafcutter bee (Megachile sp. - probably M.willughbiella?). 

We get a lot of female leafcutter bees in the garden but this is the first time I can recall seeing a male here.

I found it immediately after a torrential downpour, looking a little bedraggled and clinging with its jaws to a leaf.

I hadn't realised that they have such beautiful eyes.

Thursday, June 25, 2015

Nursery web spider

Although some spiders have a fearsome reputation, there’s no denying that others have endearing qualities – and none more so than the nursery web spider Pisaura mirabilis, one of our larger native species, growing up to about an inch long. It's quite common in our region in grassy places, where it spends much of the time hunting insects on the ground or sunbathing on leaves. 

Its peculiar way of resting with its front two pairs of legs held close together, so that at first glance it appears to have only six rather than eight legs, makes it easily recognisable.

The one in the pictures below lives in the garden of my eldest son and his partner, near Blaydon.

 When the time for courtship arrives in early summer the male spider catches a fly, wraps it in silk and presents it as a gift to a potential mate. Sometimes, if he can’t catch a fly, he’ll present her with a gift-wrapped piece of debris instead but it seems that the size of his gift, rather than its quality, is the crucial factor in determining whether she’ll choose him as a mate.

It's the thought that counts ...... as any bloke will tell you if he's forgotten his wedding anniversary then bought his wife a last-minute bunch of flowers in a petrol station.

If she does accept his advances she'll eventually produce a ball of eggs wrapped in white silk that she carries in her jaws, slung under her body, until they are almost ready to hatch. The cocoon is so large that she is forced to walk around on tiptoe, to keep it clear of the ground.

What happens next is a remarkable example of spider maternal instinct. By the time that her eggs have matured the grasses have grown tall and she climbs to the top and binds several together with silk. Then in the space below she weaves a tent, deposits her eggs inside, nibbles through the cocoon so that the spiderlings can hatch and then finally seals them inside their silken nursery. She’ll stand guard while they grow large enough to take their first steps into the outside world. 

This particular spider is unusual in that it has recently lost its right front leg and is regenerating a new one - in the picture above it's the dark-coloured leg at the bottom of the picture.

You can see the new leg, almost black and at 8 o'clock, in this closer image. Spiders can regenerate lost limbs will they are still growing and still moulting their exoskeleton, but once they reach their final moult at maturity they can't replace lost legs.


Sunday, June 21, 2015

Longhorn moths

Last week Mark Cocker wrote a fascinating Guardian Country Diary about the yellow-barred longhorn moth Nemophora degeerella  (click here to read his piece). 

By a lucky coincidence, when we visited my eldest son and his partner today their garden at Winlaton Mill near Blaydon was home to a small swarm of these little moths with amazingly long antennae. 

Part of the charm of these moths lies in their courtship 'dances' when they flutter, hover and weave from side to side waving this outsized antennae. It's the moth equivalent of Saturday Night Fever, or maybe a break-dancing contest. They put on a stunning performance this lunchtime - must try to capture it on video next time.

Saturday, June 20, 2015

Ants as nectar thieves and pollinators

I've seen ants visiting small flowers before (like this one visiting sea milkwort) but I didn't notice the ant on this heath bedstraw until I knelt down to photograph the plant .....

..... it's just above and to the right of centre in the picture.

 On closer inspection it was clear that I wasn't just a casual visitor,,,,,

.... but was methodically moving from flower to flower, collecting something .... 

.... which I imagine was nectar rather than pollen. It might have been been transporting some pollen as it walked from flower to flower in the inflorescence but ants like this are unlikely to be very effective pollinators. 

The two-segmented waist indicates that this is an ant in the genus Myrmica.

At this point I had to beat a retreat, because its fellow ants had found their way up my trouser leg.

Thursday, June 18, 2015

Meadow saxifrage

Thursday's Guardian Country Diary is all about this very attractive little flower, meadow saxifrage Saxifraga granulata. It's a species of meadows and pastures that has been in continuous decline for decades thanks to the 'improvement' of old grasslands with fertilisers and selective herbicides, which favour grasses and lead to a decline in wild flower diversity.

Fortunately there are still a few places in Teesdale where you can see it in profusion and one of the best sites is in the meadows that surround ....

.....the ruins of Egglestone Abbey in Teesdale.

You can read more about the history of the abbey by clicking here.

Meadow saxifrage thrives on the slopes leading up to the castle walls....

...... covering them in a haze of white flowers ...

..... and merging into the buttercups in the meadow below.

The most picturesque way to approach the abbey is via the footpath that runs over this tiny packhorse bridge, next to a more recent road bridge.

The packhorse bridge spans Thorsgill which flows into the river Tees about fifty metres downstream from this point.

The view from the bridge, along this little valley, can't have changed very much since the White Canons, who worshipped in the abbey, last passed this way over 500 years ago.

The valley has a fine population of meadow saxifrage too. It tends to grow in dense groups in the grass because it produces clusters of tiny buds called bulbils (the granules that the specific name granulata refers to) when the flowers and foliage die down in July, so when they sprout next year a whole group of plants grow up where only one existed before. The bulbils are also carried around in mud on the feet of cattle, which unwittingly plant it in their footsteps. 

Saturday, June 13, 2015

Butterwort: a botanical Jekyll and Hyde

Carnivorous butterwort Pinguicula vulgaris plants grow amongst the ruins of an old lead mine at Westgate in Weardale. This is a plant with a Jekyll and Hyde personality. On the one hand there's that rosette of sickly yellow leaves, covered in sticky mucilage, that trap and digest small insects (click here to see how they do it). Most of its prey is composed of ants and small flies.

On the other hand, it produces these charming flowers that need to be pollinated by flying insects, principally butterflies and bees. This is a plant that either eats insects or exploits them.

Butterwort blooms have a forest of short hairs in the throat of the flower. There has been a lot of speculation about their role but a plausible explanation is that they act as a barrier to insects that are too small to be effective pollinators; the hairs would steal nectar, but would offer no impediment to the long tongue of a bee or butterfly.

Butterwort isn't very common in Weardale but is more plentiful in Teesdale. Many years ago I visited a site on a small plateau on the edge of the moors where water constainly trickled over it, creating a mire full of interesting bog plants. As I looked over the edge of the plateau I saw a haze of these little mauve flowers just above the ground - there must have been many hundreds of plants in bloom. Must go back, to see if they are still there.

Wednesday, June 10, 2015

Every leaf is a mite metropolis

Insects begin to attack tree leaves almost as soon as they emerge from buds in spring. Some eat foliage but others turn leaves into secure homes.......... 

......... like these little red galls on sycamore leaves produced by a microscopic mite called Eriophyes macrorhynchus aceribus.

These little eruptions on the surface of an alder leaf are caused by another eriophyid mite, Eriophyes laevis inangularis.

Eriophyid mites are not insects but are related to spiders. 

This is the underside of the leaf, with the little yellow, sausage-shaped mites crawling around the entrances to the chambers, which are lined with nutritive cells that provide sustenance for the mites.

Here they are at higher magnification .........

............ and at still higher magnification, when the elongated body with four legs at the head end is visible in the mite in the top, left-hand corner. Each chamber is home to a brood of mites and a tree with a severe infestation could be covered with hundreds of thousands of them. 

These are three of the mites, each being about one fifth of a millimetre long, with only four legs.

The outer cuticle of the animal has a distinct pattern that differs between species, although the easiest way to identify species is via the symptoms that they cause on the host plant.

Here is the head, legs and cuticle patterning at higher magnification.