Sunday, January 25, 2015

Honeybees in January


Two days ago we had snow on the ground and freezing winds. Then the thaw arrived.






































Today, at mid-day, it was like spring, with warm sunshine coaxing out honeybees in our son's back garden at Winlaton Mill near Gateshead.























The bees were busy collecting pollen from Viburnum tinus. There as also a bumblebee out, but it flew away over the fence before I could see what species it was of take a photograph.






































This one had full pollen baskets

More on winter honeybees here


Thursday, January 22, 2015

Newly-hatched lacewing larva

I found this amongst some old colour transparencies that I took about 20 years ago. It shows a newly hatched lacewing larva, climbing out of its long-stalked egg that's attached to a hawthorn leaf.






































For some more images of a predatory lacewing larva, carrying the corpses of its victims on the bristles on its back, click here


Wednesday, January 21, 2015

A moss with teeth


These are the ripe spore capsules of cypress-leaved plait moss Hypnum cupressiforme - a moss with teeth.


Many mosses have teeth - peristome teeth - that surround the mouth of the capsule and regulate the dispersal of the spores. They're highly sensitive to changes in atmospheric humidity, so in dry air they curl back and allow the spores to be shaken out, just a few at a time, when the capsule vibrates on its stalk.

























It's fascinating to watch the teeth uncurl and then curl under the microscope when you breath on them. They seem to be alive, although they're really formed from dead cell walls that react to changes in atmospheric moisture in the same way as the scales of a pine cone.


Monday, January 19, 2015

Snakefly


Back in 1974, when I worked in a research station at Wellesbourne in Warwickshire, I used to take a regular lunchtime walk along the footpath across the farm. One day I spotted this extraordinary insect - a snakefly Raphidia notata - on a cow parsley umbel. 

In those days I had a very basic camera and could only afford black and white film, but I managed to take some photographs. Yesterday I found the negatives (that I'd never printed) 40 years after I took them.

This is the only time I've ever found this rather uncommon insect. I've been looking for another for 40 years, with no luck, but still hope that one might wander into my field of view, so that I can photograph it in colour with better equipment.



Snakeflies belong to the insect order Neuroptera, which also includes alder flies and lacewing flies, and their distinctive feature is that extraordinary elongated neck.


This specimen was a female. That long, curved ovipositor is used for laying eggs in the bark crevices of oak trees.


Snakeflies are predators, feeding on other, smaller insects. I was able to watch this one hunting aphids in a cow parsley umbel.











That long neck is useful for reaching forward through narrow gaps to reach prey, like .....


... this aphid that it has impaled in its jaws.






































Click here for more information about snake flies

Thursday, January 15, 2015

A Golden Wall

Thursday's Guardian Country Diary is about this remarkable 'golden' wall at Hexham, in Northumberland's Tyne valley. It's a retaining wall beside the main Carlisle to Newcastle railway line, that crosses the Tyne just beyond that bridge in the distance and passes this point at head height.







The golden covering is caused by an alga called Trentepohlia aurea.


It spends the drier months of the year as a  powdery deposit on rocks and tree trunks but when it's wet the alga grows into a forest of minute filaments, forming a dense mat on the surface.
























You can see the filaments in this close-up, grouped together to form golden cushions that are a few millimetres in diameter. This wall is constantly wet, due to water percolating through from the railway track bed, so conditions are near-perfect for the growth of the alga.





















When the tufts coalesce into a golden carpet they provides a very striking back-drop for other plants that are colonising the wall, like this ivy and .....



The liverwort Conocephalum conicum, also known as snakewort. Its surface is divided into small polygons, each with an air pore at its centre, giving it a resemblance to green snakes' skin.


There are other liverworts on the wetter sections of the wall, including this one which I think is Pellia endiviifolia.





















The crevices are home to mosses and this little fern with leathery fronds - wall rue Asplenium ruta-muraria.



















The alga seems to thrive particularly well on the cement but there are patches of lichen on some of the stones. A close look at this one revealed ....









































.... these fungal fruiting bodies, which look like tiny pink toadstools. I think this is a species in the genus Baeomyces.

























Another lichen, this time .....






































... with fruiting bodies (apothecia)  that look like minute disks of liquorice. A species of Lecidea?






































This lichen is a Cladonia species, probably C. fimbriata

Lichens are formed by the symbiotic association between a fungus and an alga and it's very likely that the algal symbiont of some of the lichens on this wall is Trentepohlia






































Back now for a closer look at the alga Trentepohlia, this time under the microscope.






































Under low magnification (c. x40) with a stereo-microscope you can see the forest of algal filaments that make up those orange cushions, while ....



....... here, under a compound microscope (x100) you can see the cells that make up the filaments, and .....







































.... at a higher magnification still (c. x400) you can see the granular, pigmented contents of the cells.

There are animals living in the crevices in this wall, including the fearsome snake-back spider - but that's another story.



Saturday, January 10, 2015

Mothing in the 1830s








































I found this rather battered copy of James Duncan's Guide to British Moths and Sphinxes [hawk-moths], published in 1836, in an antiquarian bookshop. The hand-coloured plates are particularly attractive, although some are missing (no death's head hawk-moth, unfortunately). They show the moths in colour against plants drawn in outline in the background. Double-click the images for a larger view.


























This is the delightful frontispiece.







































Hummingbird hawk-moth and caterpillar,Broad-bordered bee hawk-moth, Narrow-bordered bee hawk-moth






































Lime hawk-moth, Privet hawk-moth and caterpillar






































Red underwing and Clifden Nonpareil (which has been described as 'the Holy Grail of British Moths'


















You can read a digital version of the book by clicking here   The plates are all grouped at the end of the book in this version.




Wednesday, January 7, 2015

Ivy - the all-year-round carbon dioxide fixer


Ivy's flowers provide a wonderful nectar and  pollen resource for insects in autumn (see some examples at the bottom of this post) and its berries are a vital food  resource for migrant birds in early spring, but it also has another important attribute with more general implications.

As an evergreen that stores carbon in its woody trunk, ivy is an all year-round carbon dioxide fixer, constantly removing the gas from the atmosphere. In that respect it contributes towards combatting the build-up of carbon dioxide in the atmosphere, which is the underlying cause of global climate change.






































Deciduous trees like this ash have a short growing growing season in our seasonal climate. It comes into leaf in May and sheds its foliage in September, so for about half the year it fixes no carbon dioxide at all. But when it supports a luxuriant growth of ivy the two organisms together fix carbon dioxide 365 days a year.







































The combined efforts of an ash tree with ivy cladding are likely to be more effective at fixing atmospheric carbon dioxide than an ash tree alone.




The tangle of  thick, woody ivy stems on this sycamore are as effective a store of carbon as the tree's trunk.




Ivy can even turn a dead tree into a carbon dioxide fixing pillar of evergreen foliage, as it did with this dead oak at Egglestone in Teesdale a few years ago. Even better, in autumn this stump became a tower of flowers, humming with insects that came for the nectar and pollen. In spring it was covered in berries.

Another example, at Wolsingham in Weardale.

Sadly, there are still plenty of ivy-haters around who are convinced that ivy is a parasite (it isn't, it just uses trees for support). They'll usually also advance the argument that a top-heavy mass of ivy is likely to bring trees down in winter gales, but most trees that are felled in this way are moribund anyway and topple because they have already been weakened by root-rotting fungi, not by ivy. Logically, a good cladding of well-rooted ivy stems is more likely to anchor a shaky tree, delaying its demise. 

The fact that trees that have been killed by fungi often have a healthy covering of ivy suggests that it might well be resistant to some of the fungi that kill trees.

From all of this you might have gathered that I'm something of an ivy enthusiast - not least because of the insect fauna that its flowers attract in autumn. All of the pictures below were taken in a few minutes late last October on another ivy clad tree just across the road from the oak-clad stump pictured above.