Thursday, May 29, 2014

Sawfly larva

Twitter can be a wonderful resource. Within half an hour of posting a request for help in identifying this sawfly larva, it had been identified by @SK53onOSM and Colin Perkins (@PershoreColin) as Apethymus serotinus.

For pictures of the adult insect, visit this blog

It exhibited typical sawfly larva behaviour when I gave it a gentle prod ....

........ curling itself up into a spiral.

The key distinction between a lepidopteran (butterfly or moth) caterpillar and a sawfly caterpillar lies in the number of legs: both have three pairs of true legs at the front but lepidopteran larvae only have four pairs of prolegs behind, whereas sawfly larvae have six or more pairs of prolegs. 

Tuesday, May 27, 2014

A Day on the Durham coast

Some plants and animals from a day walking on the cliffs between Seaham and Hawthorn Dene on the Durham coast last week

Dozens of fully grown drinker moth caterpillars on the steps leading down to Blast beach ...

..... some had even made it all the way down to the beach

Masses of bird'sfoot trefoil in full bloom on the edge of the limestone quarry

Bloody cranesbill coming into bloom on he magnesian limestone grassland

Wonderful display of buttercups in the meadows at Hawthorn Dene

Not many early purple orchids, but some nice specimens

Some glorious displays of hawthorn near Hawthorn Dene. Best year for hawthorn blossom that I can remember

Common milkwort around the quarry area

There's not a lot of sea pink along this coastline but in full bloom

A goldfinch that seemed to be ill and was reluctant to fly, but with no visible signs of injury

.... and finally, fulmars soaring along the cliffs

Wednesday, May 21, 2014

Wildlife in an old lead mine

Thursday's Guardian Country Diary describes some of the wildlife that has colonised the old disused lead mines at Westgate in Weardale. Many of the industrial processes that took place here (and ceased early in the 20th. century) involved the use of water, to power a hydraulic engine and to separate lighter stone from heavier lead ore (galena). The legacy is an excellent habitat for wetland wildlife which is now a Site of Special Scientific Interest.

I almost trod on this down-in-the-mouth toad, whose colour blended so well with the mosses around one of the shallow pools where it had spawned. You can see the ridge just behind its eye where the poison glands are located, which deter predators.

In this view you can see most of the main site, with Middlehope burn snaking through the valley. In the foreground you can see bridge parapets for the railway bridge that crossed the burn - ore was taken out on railway trucks pulled by horses. In the middle distance, just to the left of the third bend in the burn, you can see a rectangular depression with a pool of water in the centre. This was once a reservoir.

The reservoir is fed by water flowing out of this mine entrance, known as White's Level. The tunnel is just large enough to accommodate a small pony. Some of these mine levels stretch for miles under the hillside but are now lethal because some lead to vertical shafts where miners were winched down in baskets to tunnels that followed lead veins at lower levels in the strata.

The water flows out through a bed of watercress and into...

.... the silted up reservoir, mentioned earlier. This is a great site for dragonflies in summer, and also a breeding site for toads. The retaining wall on the left, like most of the walls of the mine ruins that were constructed from limestone blocks, is excellent habitat for ferns, like .... 

... the dainty brittle bladder fern.

These are ruins of lead mine buildings downstream, with more waterlogged ground. The key elements for plant growth - soluble nitrogen and phosphorus - are rapidly washed from the soil by rainfall and flowing water, so some of the plants that grow here are adapted to obtaining these minerals by other means.

This is marsh lousewort, a partial parasite on the roots of grasses, that connects with their root systems and siphons off their mineral supplies, and ....

.... these are plants of butterwort. Those rosettes of sickly yellow-green leaves are covered in sticky mucilage glands that trap small insects, which are then digested by enzymes secrete by the leaves.

Downstream Middlehope burn flows through the sheltered, wooded valley known as Slitt woods and ....

...... when it reaches Westgate in Weardale flows over a series of picturesque waterfalls into the river Wear.

Sunday, May 18, 2014

Renewing my acquaintance with knee holly

Half a century ago, when I was enjoying a feral childhood in the foothills of the South Downs in Sussex, I'd sometimes trespass through a hornbeam coppice on my way home and would pass clumps of a strange, painfully spiky plant that bore weird, purple starfish-shaped flowers in the middle of its leaves, that were followed in winter by very large scarlet berries. 

A few years later, when I was studying A level botany under the guidance of an inspirational Yorkshire botanist called Bill Jackson, I finally understood what I had been looking at. The plant was butchers' broom Ruscus aculeatus and Bill pointed out that, incredible as I might seem, this plant was a member of the lily family. And he pointed out that the 'leaves' weren't leaves at all, but were flattened stems called cladodes.

Fast-forward fifty years, to Durham University Botanic Garden this afternoon and a feeling of deja vu, because there in the shrub  border was butchers bloom, complete with some of those starfish-shaped little purple flowers. It was good to see it again.

It was never a very common plant when I was a kid but I'm glad to see that it seems to be holding its own, judging from the account in the Atlas of the British and Irish Flora. It's only native in the southern counties and up here in Durham it's a long way from home. It spreads slowly via creeping rhizomes and in the past was harvested and bound into bunches for sweeping sawdust from butchers' floors - hence the common name. Its spectacular berries meant that it was also cut as a Christmas decoration. The plant is dioecious (with separate male and female plants) and you need both sexes if you want the spectacular scarlet berries, so the hornbeam coppice must had had both present. 

One of the other things that drew it to my attention as a small boy in shorts was that its stiff, spiny cladodes could give you some painful scratches on your bare legs so its alternative name - knee holly - was particularly apt.

Monday, May 12, 2014

A micro-moth with a liking for germander speedwell

The grassland areas of Low Burnhall Woodland Trust reserve have some very fine patches of germander speedwell in bloom at the moment, and they seem to be very popular with micro-moths.

As far as I can tell this tiny insect is the cock'sfoot moth Glyphipteryx simpliciella, which breeds on cock'sfoot grass but clearly finds these speedwell flowers very attractive.

Sunday, May 11, 2014

Oak apple and Currant galls

This oak, just coming into leaf beside the river Tyne at Wylam yesterday, was carrying both oak apple galls and currant galls.

The big, spongy oak apple is caused by the tiny wasp Biorhiza pallida, which lays its eggs as the base of an oak bud and causes it to swell into this large gall that's home to up to 30 of the gall wasp's grubs. After it matures in July the hatching adults chew their way out, leaving distinctive exit holes. 

Oak apples contain either all male or all female wasps but when they emerge they mate and the fertilised females then lay their eggs on the oak's rootlets, when they form a much smaller woody gall. Only females emerge from these and in late winter climb the oak's trunk and lay eggs to form the next generation oak apples.

The small red, spherical galls dangling under the oak apple are currant galls formed in the catkin of the oak, when the gall wasp Neuroterus quercus-baccarum lays its eggs in the male flowers. Each currant gall contains a single grub  and either males or females hatch in June. After mating the female lays her eggs on the underside of the oak leaves, where they form the familiar spangle galls that cover the lower surface of the leaf in autumn.

Spangle galls drop off shortly before the leaves fall in autumn, then in spring females emerge and lay eggs in the oak's catkins, producing currant galls again.

For more pictures of plant galls click here

Thursday, May 8, 2014


Thursday's Guardian Country Diary is about an encounter with snipe on Chapel Fell in Weardale.

Usually the first hint that there are snipe around comes from the sound of males during their territorial 'drumming' flights, when they fly a switchback course around their territory. During their dives single feathers on either side of the tail stick out (see photo above) and produce a strange reverbatory bleating sound.  As soon as the sound reaches the ground the snipe has already begun to climb again, so it's not easy to find the high-flying fast-moving bird against a clear blue sky from the drumming sound alone.

When this one had finished its display flight it landed on a fence post close to where I was standing and began its mating call - a weird metranomic tick-a, tick-a call that rises in volume then suddenly stops, restarting after a brief interval. The bird soon flew off, but .....

.... not very far, landing on this tall pipe and calling all over again. It seemed reluctant to leave and I discovered why ...

.... when the female casually walked out of a muddy patch of rushes just a few feet away from the wall that I was leaning on. The camouflage from her mottled plumage was exquisite and when she stood still it was easy to lose sight of her. I had time for just one quick picture before she sprang and zig-zagged away across the fell, towards her consort.

A memorable encounter.

Saturday, May 3, 2014

A spot of rock-pooling

Mid-day low tide so went rock-pooling today at Whitburn rocks, Sunderland. It's not exactly the Great Barrier Reef but you can usually find something interesting.

Who can resist turning over rocks on the seashore? This shanny (?) Lipophrys pholis was under one in the middle shore and wriggled out of the water when disturbed.

Lots of young edible crabs, that adopt this characteristic pose when you pick them up by their crimped-pie-crust carapaces

This one was tiny, smaller than my thumbnail, and judging by its colour had recently moulted.

The rock pools were full of hermit crabs, with their jerky walk that makes them look like automata.

I think this is a very young shore crab, half-hidden in the wet sand under a rock, and .....

....... this is a larger one, very disgruntled and in defensive pose.

This was probably the most interesting find - a grey topshell that had recently spawned - you can see the developing embryos in the jelly, from which they'll hatch and enjoy a brief period as planktonic larvae.