Thursday, October 23, 2014

Under the skin of a sycamore


Thursday's Guardian Country Diary is about the remarkable range of small invertebrates that live under the flaking bark of old sycamore trees.























When the bole of an old sycamore tree expands the old rigid bark cracks and begins to curl at the edges, while ....























.... a fresh, new layer of bark forms underneath. It might not look very attractive but these bark flakes, some as large as a slice of toast, take a long time to fall off and while they are still attached harbour a remarkable fauna of small invertebrates underneath. Here's a selection, most of which I've yet to ID.



































Millipedes, a hatched moth pupa and some unidentified cocooons 






















Lots more millipedes - these were just a few from under two bark scales - if this sample is representative there must have been hundreds sheltering under the bark of this tree
















A minute scarlet mite



















A rather beautiful little money spider, Gonatium rubens























A huddle of earwigs ....























... that raised their tail forceps in defence when they were suddenly exposed to the light. Male left, female on the right.




































A spider that lives in a silken tent under the bark























Lots of slugs in areas where the bark is permanently damp, where rain water trickles down the tree trunk ..























.... together with snails ......























...... and woodlice















Another moth pupa, that looks as though it hatched successfully.


Sycamore sits low in the league table for tree foliage that supports insect biodiversity - a 1961 research paper on the subject found only 15 species, compared with the 284 hosted by oak (click here for details). But a quick look under the flaky bark of old sycamores casts them in a more favourable light, as a sheltered habitat for a host of invertebrates. 

The few examples shown here were just from a height that I could reach - there may well be a different array of species higher up the trunk and the hosted species most probably vary depending on the aspect (sunny & south facing or shaded & north-facing). Moisture must play a role too because there are well defined runnels where rainwater flows down the trunk from the branches and the bark there is always moist and often very wet. All in all, flaking sycamore bark is probably quite a complex habitat, with many interesting interactions between species that inhabit it.


Wednesday, October 15, 2014

Pine cone bug


Found this lovely little pine cone bug Gastrodes grossipes scurrying around below some Scots pines, near Wolsingham in Weardale today. 



















The adult bugs overwinters in a secure spot and mate soon after emergence in spring. The nymphs that hatch from the eggs feed on the soft tissues of pine - especially the developing green cones, and reach maturity in early autumn.

Adult bugs often shelter between the open scales of mature pine cones.

Friday, October 10, 2014

Psychedelic Spindle

I was a teenager in the 1960s, so inevitably the vibrant colours of these spindle Euonymus europaeus fruits remind me of the colours used in psychedelic art during the period. This must surely be our most colourful hedgerow tree, not least because its foliage also turns crimson in October.

























When the fruit splits open it reveals the seeds, which are covered in an extra fleshy orange layer known as the aril, which makes them attractive to birds. Very few British native plants have seeds with arils, although they are common in the tropical flora - the fleshy edible part of a lychee is an aril.

Sadly, spindle is now an uncommon hedgerow tree through much of its range because in winter it's the alternative host of black bean aphid that infests bean crops in summer, so it has been deliberately eradicated in some arable-growing areas. 

Thursday, October 9, 2014

Birch Shield Bug

Today's Guardian Country Diary is about this delightful family of birch shield bugs that I found feeding on birch seed catkins, beside a footpath along the river Tyne at Wylam.




This is a nymph, two moults away from becoming an adult, with the most amazing 'smiley face' markings on its abdomen - an insect emoticon.






































And here it is feeding alongside its mother, on a birch seed catkin.


Tuesday, October 7, 2014

Heterobasidion annosum - a notorious, tree-killing bracket fungus

We found this impressive specimen of the root rot bracket fungus Heterobasidion annosum in Hamsterley Forest at the weekend. The roots of the Norway spruce that it was growing on will have been largely destroyed by the time the fungal fructification reaches this stage.



The bracket was actively releasing spores - notice the dense white covering on the ground under the bracket. They are often dispersed by soil animals.






















Root rot is one of the most damaging tree pathogens and the surrounding trees, as well as this one, are likely to be fatally infected.









Monday, October 6, 2014

Yew



This is the time of year when yew 'berries' begin to become conspicuous. Yew is one of only three British native species belonging to that division of the plant kingdom known as the gymnosperms - seed-producing plants that don't have flowers and don't enclose their seeds in an ovary to form a fruit. The other two are juniper (whose seed has a succulent outer coating - seed picture at the bottom of this post) and Scots pine (which carries its seeds in woody cones - see picture below)





















In this picture you can seed the fully formed yew seed on the right, half covered by a pale green cup. This is the tissue that quickly expands to form the scarlet succulent aril, that you can see half-formed on the seed on the left. This squashy cup is attractive to birds that disperse the seeds, effectively judging from the numerous seedlings that appear in places where birds perch, such as crevices in old stone walls after the seed passes unharmed through the bird's gut. The seed itself is deadly poisonous to mammals but I've watched nuthatches wedge it in a bark crevice, hammer it open and eat it.



























Here's a fully formed aril, which almost completely encloses the seed, like a scarlet doughnut.




















Juniper 'berries'







































Scots pine cone



Saturday, October 4, 2014

Greenfly guzzler


I found this large hoverfly larva in Teesdale yesterday and watched it feeding on aphids. A gruesome spectacle - it caught them tail-first and they were still waving their legs and antennae as they disappeared into the predator's digestive tract.






Thursday, October 2, 2014

Vandal identified


This year the Korean fir Abies koreana in our garden has produced its best cone crop ever. They usually stay on the tree well into winter but over the last week they've begun to disintegrate, with more being reduced every day to a spiky spindle. I thought it might be the dry autumn that was causing the cones' premature destruction but this morning I discovered the real cause..... 






















.... and this is the culprit. I watched for half an hour while it made made repeated visits, pulling the cones apart.





































This is what it was after - the seeds, which have purple papery wings. There are two seeds attached to each of those fan-shaped woody cone scales.
























The bird is totally obsessed with plundering the food store that it has discovered - so much so that it allows us to approach quite closely to watch. At the current rate it will have trashed all the cones within about a week.
























Korean fir is an ideal specimen conifer for a small garden, producing a reliable cone crop when just a few years old. Ours is growing in a very large pot and doubles up as a Christmas tree. The attractive cones are held upright on the branches and are purple when they first develop, ripening to brown and topped with very fragrant resin. And, as it turns out, excellent food for coal tits and if brings them into the garden, that's a plus.


Thursday, September 25, 2014

Ants and Adders

Thursday's Guardian Country Diary is an account of an encounter with ants and adders


























This massive wood ant's nest is on the side of a footpath through Hamsterley Forest on the edge of Weardale in County Durham. It's four years since we last followed this path and the nest is now almost a metre tall. There's as much nest below ground as above soil level and it's probably home to well over 250,000 ants.



















The nest is thatched with dead pine needles and its surface was covered with ants, either adding more thatch or bringing back honeydew that they'd collected from aphids high in the tree canopy.







































These ants attack intruders with great ferocity. This is what happened when I poked a stick into the top of the nest. You can see the powerful jaws biting the stick .....


























..... and here you can see how the ant curls its tail underneath, to squirt formic acid at the attacker.


























Those jaws are very painful when they grip your flesh, but .....






















... not as painful as a bite from this. My wife spotted this female adder sunbathing near the ant's nest. You can see how the snake has flattened herself out to absorb as much of the warmth of the autumn sun as possible.
























While I was photographing her I noticed two young adders, about the length of my index finger, slithering away in the grass, too quickly for me to get a photograph. Evidently we were standing in a favourite adder sun-basking spot. At this point the female became more defensive, although it's hard to say whether is was because she was defending her offspring or simply because she was tired of our intrusion in her siesta.

By now the angry ants had caught up with me and were biting myleg, so it was time to leave!

For more on adders click here