All posts by Ian Alexander

Conservation, Environment, Love of Nature, Philosophy

Love of Nature? Man vs Nature? How Very Odd

There is something distinctly odd about the British love of nature. I mentioned the subject at a book launch the other day, and the person I was chatting to said, between sips of the very nice white wine and a nibble of the focaccia, that he thought the British were not really in love with nature any more as a personal activity, but were just consumers, passively and vicariously absorbing what is offered up as a commodity. I said that was ‘interesting’.

The ‘in love’ view of the British perhaps blends several different stereotypes. One is the obsolete stiff upper lip, the naturalist out in some far outpost of forgotten empire, enthusiastically carrying on studying phasmids like James Wood-Mason, writing obscure papers in the Journal of the Asiatic Society of Bengal for the benefit of anyone of similar inclination.

Another is the hugely enthusiastic amateur naturalist – the keen birdwatcher, entomologist or botanist with telescope, moth-trap or vasculum always to hand, hoping to add a species or two to a county list.

Yet another is the happy gardener, always outside – rain or shine – pruning, digging, composting, planting, watering, weeding.

The stereotype that my wine-sipping acquaintance had in mind was presumably rather different: couch potatoes, relaxing with a remote in the sitting-room, allowing an hour of television gardening with Monty Don or a year in the life of some wildlife area – the Canadian Rockies or the Great Barrier Reef, the Patagonian plains or the last surviving bit of the Sundarbans, or worse, all of the above, cut together by an editorial team with a high concept of Surviving Against All the Odds or something – to wash over their minds, leaving no particular trace other than a feeling of having seen a lot of colourful flickering images.

Personally, I doubt that picture is fair, though like all stereotypes it must make some contact with reality somewhere. People are all different, and everyone needs to relax sometimes.

A truth, though, that everyone who likes some kind of experience of nature, live or through book, film, photograph or website, is that if we’re studying or watching nature without doing something to help protect it, we are ignoring a very large existential threat indeed. Assuming we manage not to destroy ourselves in a nuclear war, we are going to have to work out how to survive an ecological disaster of our own making. Its epic proportions are becoming clear: the last time anything like this happened was at the end of the Cretaceous period 66 million years ago. Whether Luis Alvarez was right that an asteroid or comet crashed into the Earth to form the Chicxulub crater, the debris thrown into the atmosphere causing something like a nuclear winter, it is certainly the case that huge numbers of species became extinct very quickly, including all the world’s large dinosaurs (yes, I know we have the birds still with us, and they’re in the dinosaur clade) along with perhaps three quarters of all other kinds of living thing.

You may perhaps feel somewhat untroubled by the idea that the world of your grandchildren might have no tigers or rhinoceroses in it; or even that there would be no areas of rainforest outside national parks – the Amazon and the forests of Sumatra and Borneo are well on the way there already.

You might be slightly less thrilled at the news that many of the world’s hotspots for variety of animals and plants will be gone completely: as South Africa becomes warmer and drier, the whole Cape region as understood by botanists will move southwards – into the ocean – and disappear forever, that incredible wealth of flowers, all those extraordinary Proteas, will remain only as a memory.

Perhaps even that isn’t too worrying, just news from a far country? Well, the sea level will rise by several metres when the Antarctic ice-cap melts, flooding coastal plains and threatening to drown many cities.

Not a problem? Global warming, whatever may have caused it, is already making deserts expand. Droughts will become year-long from California to southern Spain, Sahel to Australia. Food prices will rise drastically; wars will be fought over water and other critical resources.

Still not your problem? Farmland all across America and Europe is already denuded of crop pollinators, especially honeybees and bumblebees. Grasses like wheat and rice are not affected, but much of your food, and vital fodder crops for farm animals – from alfalfa to zucchini – is utterly dependent on pollination, and it’s in free fall.

What is all this about? How have we got into the crazy situation that half of us – some of us anyway – love the idea of nature, love to look at it (at least the pretty bits), while the rest (ok, possibly nearly everyone, whether we like nature or not) see themselves as separate from it? How separate can we be when we depend on it absolutely for the air we breathe – all the oxygen produced by green plants – and the food we eat – all our food coming from animals and plants? What are all those student notes in English literature about ‘man v nature’? We are part of nature. It isn’t even that nature is our survival blanket. We, like all other living things, are part of an ecosystem. The mosquitoes that bite you on holiday are in no doubt that you are edible. You eat chickens or carrots, beef or beans. Billions of bacteria in your gut share that food with you, consuming some, helping you absorb the rest. Eventually, bacteria will consume you, if you don’t get yourself cremated first. You are part of nature, no doubt about it.

So, how are you going to change what you do, to help keep this system working? Right now, it’s already badly broken, and getting worse each year. We haven’t got long to fix it.

Gardening, Natural History

Insect Pests and Predators on Spinach (and Gooseberry)

Leaf miners in Spinach Beet leaf. A strip of the leaf's upper epidermis has been torn back.
Leaf miners in Spinach Beet leaf. A strip of the leaf’s upper epidermis has been torn back.

Well, I usually try to take a pretty picture to start off a posting, but this one certainly doesn’t qualify. These leaf miners grow entirely inside a leaf, in this case of Spinach Beet. As you can see, as they grow they tunnel around below the leaf’s upper epidermis, which is a translucent layer of cells, leaving it intact to provide themselves with a ready-made cover.

Underneath that sheet, a healthy leaf contains a thick green set of palisade cells in one or several layers. These are the leaf’s (and the plant’s) factory, as they are full of chloroplasts, coloured green to absorb light: they synthesize the sugars on which life depends.

Not many people would want to eat this leaf, once the leaf miner larvae – mostly moths – have been at work. The palisade layers are entirely and efficiently destroyed wherever the insects have been. All that remains is an air-space and some dark frass: all, that is, but for the plump whitish cylindrical bodies of the larvae themselves.

Ladybird larvae and eggs on Spinach leaf
Ladybird larvae and eggs on Spinach leaf

Also nesting on the spinach are some ladybirds. These have incomplete metamorphosis, the young being able to walk as well as eat from their first stage or instar. Each time they moult they change in appearance as well as in size. They mainly eat aphids, troublesome pests of many crops, so they are useful to gardeners and to any farmers who don’t want to use insecticides.

Shield Bug on Spinach
Shield Bug on Spinach

This shield bug, seen here in close-up, may look conspicuous enough, but that is the camera’s view. The insect is actually rather well camouflaged, and it generally hides under a leaf where it is in some shadow. The camouflage consists first of a general colour resemblance to its background, with its overall grass-green coloration; and as seen here, it is also disruptively patterned, with the reddish brown of its wings tending to break up its outline. Perhaps it is also somewhat countershaded, with dots stippling its back.  Bugs suck plant juices, and their larvae can be quite destructive, but they never seem to do much harm to the spinach.

There are also some green caterpillars, excellently camouflaged with a pale cream stripe all along their sides. (It might be the Hebrew Character moth.) You might expect this to be conspicuous, but it seems to be a classic piece of disruptive coloration: the stripe appears like a sun-glint specular highlight on the shiny crumpled surface of the spinach leaf, rather than part of a solid, round-bodied animal.

A Sawfly ... not on Gooseberry
A Sawfly … not on Gooseberry

A pest I know is there is the Gooseberry Sawfly. There are numerous sawflies in the garden right now, but they are all flying around the Nasturtiums, nowhere near the gooseberry bush. However… plenty of the lower leaves of the gooseberry are badly damaged by sawfly larvae, some eaten right down to the petiole, pathetic little stumps with a few short branching veins all that remains of once green foliage. What to do about it? This isn’t a how-to-garden site, but inspect your gooseberry bush(es) regularly, looking especially at the lower leaves to see if they’re being eaten. If some are, check the edges for caterpillars. If you find any, spray the bush after sunset on a dry still evening (to avoid killing the bees that are pollinating your fruit) with a garden insecticide.

Five minutes of careful searching of half-eaten gooseberry leaves failed to reveal a single larva. The cause in this case is not so much camouflage as the incredibly intense predation by Blue Tits (and Great Tits). I estimate these little birds are a hundred times better at finding caterpillars than I am. They have the advantage of getting in close – they must be able to focus down to a few centimetres, their small eyes acting as short-focus wide-angle lenses – and of being able to perch anywhere in a bush. They also get up very early, and know instinctively exactly what food looks like: small well-camouflaged caterpillars on the undersides and edges of leaves.

Zoologists suppose that birds have a ‘search image’ of the prey they are hunting: perhaps this is much the same idea as the training images that computer scientists use to teach their neural nets to recognise patterns such as faces. Once you have such an image in your brain, you almost instantly recognise your target when it appears. To give a small illustration, I remember when I had a small motorbike, I always saw bike shops everywhere; now I never notice them. My eye was attuned, like a Blue Tit’s to a caterpillar.

Product Review

Product Review: Nikon Coolpix S9400

 

Nikon Coolpix S9400: a really good pocket camera
Nikon Coolpix S9400: a really good pocket camera

I’m reviewing this excellent pocket-sized camera for just one reason: it’s ideal if you want something small, effective and reliable in your bag or pocket while you are mainly getting on with the rest of your life, such as enjoying nature. I take mine with me whenever I go out. It’s no trouble to carry, and its powerful zoom lens, anti-shake, high quality and simple but controllable operation make it extremely useful for everything from landscapes to close-ups of insects.

Large Red Damselfly, Pyrrhosoma nymphula
Getting in Close: Large Red Damselfly, using the closeup setting of the S9400

The camera starts up quickly – very helpful if you are trying to get a shot of an animal before it vanishes, and focuses quickly and reliably in a wide range of situations. It comes with automatic reduction of camera shake, specially helpful if you are using the zoom. I’d still recommend you try to find something to rest the camera on – I use a screw-on monopod as it’s lighter and quicker to use than a tripod, and is helpful for everything from photographing flowers and insects to steadying the camera for a long shot.

The good-sized sensor is much larger than that on earlier models, and it shows: the camera collects much more light, giving sharper and less grainy images, specially in poor lighting conditions.

The screen is much larger, too, and in general it works well, even in bright sunlight; if you are using full zoom with the sun shining on the screen, you need to turn up the brightness using the ‘Monitor’ menu. The only other setting I touched was to make ‘Closeup’ the chosen ‘Scene’, so as soon as I turn the dial to Scene, I’m ready to shoot closeups: very convenient.

With smartphones able to do everything from the shopping to baking bread, you may be wondering why you need a camera at all. There are several good answers to this (tick all that apply):

  • if you’re going to drop it in the mud/pond etc, better have something cheaper than a high-end smartphone
  • for steady handheld shots, this is far better
  • since it has a flat base, and takes a tripod or monopod, you can get much steadier shots
  • the optical zoom (4.5 to 81 mm, equivalent to an extraordinary 25-450 mm range on a traditional SLR camera) and the large lens (F3.4 at its best) are far better than anything a phone’s camera lens can manage (and there’s digital zoom and crop too)
  • the video is HD if you need it.

But the simple truth is that this is a very handy small camera that takes just the shots you need to record your experiences with wildlife and scenery large and small. It isn’t the same as having a high-end SLR with a suitcase full of heavy expensive lenses to hand, but it is much more portable, a great deal cheaper, and it takes great pictures.

Buy it from Amazon.com
Buy it from Amazon.co.uk

You’ll need to get an SDHC memory card for it, and a carry case too.  A 16 Gigabyte card will store well over 3000 images. It comes with a USB cable and a Mains-to-USB plug so you can charge the battery without removing it from the camera. If you want to charge it faster (not very necessary, probably) or to charge a spare battery then you’ll need a separate charger too.

Nikon has newer / more expensive cameras. These will be excellent too; I chose this model for its current low price (I don’t mind if something happens to it, so I feel relaxed about carrying it everywhere) and high quality.

Natural History, Nature Reserves

Thursley Common: a Special Place

Heath landscape at Thursley with birch scrub, scattered pines
Heath landscape at Thursley with birch scrub, scattered pines

Thursley Common is one of those few, special places where the quiet visitor is almost guaranteed a beautiful experience of nature, at least if busy weekends are avoided. The area of a few hundred hectares offers several habitats, all acid: pine forest; dry sandy heath with heather, gorse and birch scrub, ideal for Whitethroats and Stonechats; acid bog with sphagnum, bog-cotton, marsh orchid, round-leaved sundew; bog pools buzzing with dragonflies; open water with teal and tufted duck.

Marsh Orchid, Round-Leaved Sundew at its foot, Thursley
Marsh Orchid, Round-Leaved Sundew at its foot, Thursley Common
Dragonfly habitat: bog pools at Thursley
Dragonfly habitat: bog pools at Thursley; in the background, white of bog cotton, birch scrub and pine forest

Over the pools were half-a-dozen swallows in a loose flock, mostly flying high, keeping a wary eye out for hobbies. Two hobbies at least flew across the heath on their long grey wings, diving at speed to snatch dragonflies low over the water. A cuckoo called from the pines; another replied cuck-uck-oo from the other side; one flew hawklike across the heath, its wings remaining almost entirely below its body, an odd and very distinctive flight pattern.

Female Four-Spotted Chaser
Female Four-Spotted Chaser basking over a bog pool, Thursley
Four-Spotted Chasers have a distinctive jizz, being generally brown, flying fast, and indeed the males aggressively chase off rivals. Today there were several pairs mating in flight; unlike many other dragonflies, they do not settle to form a “wheel”, but soon separate, the female at once starting to lay eggs, darting down to the water to dab her abdomen repeatedly.
Large Red Damselfly, Pyrrhosoma nymphula
Large Red Damselfly, Pyrrhosoma nymphula male on heather at Thursley
Large Red Damselflies were hardly in evidence near the water, but were around in small numbers on the heather, or basking on the boardwalk. Nearby, a pair of Reed Buntings blundered in and out of the bushes, the male handsome with his black head and white collar, singing his slow brief song. A Goldcrest squeaked its unbelievably high notes from the tops of the pine trees. A Tree Pipit’s repetitive but slightly random riff rang out again and again from somewhere in the same trees; the species, still marked by the book as ‘abundant’ (that’s a 2 not a 1, however), ‘breeds locally’ in places like this.
Bog-Cotton, Molinia
Bog-Cotton, Molinia
It is always a pleasure, too, to see the fluffy white seed-heads of Bog-Cotton. The thin fibres are too brittle to spin, so our native ‘cotton’ remains a symbol of wild and lonely places, from the mountains of Snowdonia to the Pennines. It’s a reminder of just how extensive the heathlands of Southern England once were, Cobbett’s “rascally heaths” famously extending all the way from the Marlborough Downs to the fringes of London. His opinion, loudly voiced in his Rural Rides, was that these unimproved lands were wasted, a sign of lack of proper agriculture. The Dig for Victory! campaign in the Second World War caused many areas of marginal land to be ploughed up, including acid heaths, alkaline chalk grassland, and neutral flowery meadows: all were lost by the thousands of acres in a desperate attempt to increase Britain’s arable production. That led, of course, to the surplus production of the Common Market years, the destruction of farmland wildlife accelerated by grants to grub out hedges, while the use of pesticides of all kinds created marvellously clean crops that even that old badger of a critical farmer, Cobbett himself, would have heartily approved of. The one small problem was that the crops were so clean that there were no wild flowers to support the bees that used to pollinate the fruit trees, the clover, beans and alfalfa, the cabbages and turnips and oilseed rape, the potatoes and vegetables that feed the nation. The cereals themselves need no bees, their grass pollen blowing in the wind: but the rest of the crops are tied to a more balanced ecology. Thus I meditated, even as I enjoyed a nostalgic glimpse of Molinia, the Bog-Cotton; and so it is that delight in nature’s beauty is tinged with sadness at the mess we’re in.
Tiny yellow clubs of Bog Beacon fungus, Mitrula paludosa, in marsh
Tiny yellow clubs of Bog Beacon fungus, Mitrula paludosa, by bog pool at Thursley
I was delighted to see the small but bright yellow Bog Beacon fungus. It appears as small clubs with white stalks, and it only grows on dead vegetation in acid bogs. Its specific name ‘paludosa’ means ‘of the marsh’. A single Broad-Bodied Chaser dragonfly scooted swiftly across a small pond.
Stonechat on fencepost of training area near Thursley
Stonechat on fencepost of Hankley Common training area near Thursley
Stonechat males displayed atop gorse bushes or fence posts, or dived into the bushes for cover, appearing nearly all black from above, with a bold white flash on each wing. Several young ones perched lower down in the gorse, much browner and more streaky than their fathers. They are rather few and far between on the Common itself; more on the training ground just across the road at Hankley Common. Like Thursley Common, the land has remained wild because the army needed it for training; so the Second World War both destroyed much of the wildlife value of our farmland, and saved some places from the general destruction.
Natural History

Bracken Fiddleheads as Food

Today I watched as a young East Asian family with a small child wandered carefully, heads bowed, through the bracken (Pteridium aquilinum), picking young not-yet-unrolled shoots known as fiddleheads — they do look rather like the curled ends of violins — for use as a vegetable. It is commonly eaten in Japan, China and Korea.

Bracken, including young shoots, is carcinogenic in animals, and herbivores like horses generally avoid it if they can. The main toxin is ptaquiloside. Richard Mabey’s Food for Free mentions bracken only once, to say that it is carcinogenic, and omits it from the main text. Some scientists suspect that the high incidence of stomach cancer in Japan is connected to the consumption of bracken.

It was chilling, on a fine hot day, to consider the danger that family were putting themselves in. On the other hand, if they select only young shoots, the dose is as low as possible — the plants have not had time to accumulate toxins in newly-grown parts. And all of us consume substances — sugar, salt, nitrates in ham and sausages, … — not to mention alcohol, which are certainly not good for us. Can you have a natural history of human beings? I can’t see why not.

Natural History

Bluetits: Flown the Nest

Blue Tit Update: after several weeks of frantic activity by the two parent birds until yesterday, today the nestbox is empty and unattended. All the young and their parents have left. They aren’t in sight at the moment: most likely they are not far away, as a family party. There are no signs of predation, and nestboxes mounted high on a wall are in any case very good protection against all our common nest predators.

Conservation, Environment

The Unchanging Woods, Maybe

You enter the wood — and you might just as well be in the Middle Ages. When I hear people speak of the Dark Ages, I remind myself how in those days the sun shone in just the same way as it does now, and the flowers glittered in woods where there was no difference from what we see today. … Inside the wood we are in the past as well as in the present.

With these thoughts, John Stewart Collis draws his book Down to Earth, now the second part of the combined volume The Worm Forgives the Plough (see my book review) to a close.

And in a way his thoughts from 1947 are still true today: nature is timeless, specially in a wood.

But in another way, the woods of 2014 are very different from those of 1947. The old practice of coppicing is all but dead: a few nature reserves struggle to practise something approaching it; enlightened landowners fell woods in patches rather than clear-felling whole landscapes, approximating the mosaic of new glades, fine old trees, brushwood, young trees and woodland edges bursting with songbirds that characterise true coppice. Often, in the old way of things, coppicing deliberately left behind a few ‘standards’ here and there, fine straight oaks or other hardwoods to grow large timbers for building ships or roof beams. Now, woods are more likely to be managed industrially for timber, or are sadly neglected with ivy on every trunk, brambles all around the forest floor.

Reeves' Muntjac, introduced from China, are now widespread across Britain and Europe
Reeves’ Muntjac, introduced from China, are now widespread across Britain and Europe

And it gets worse. Where Collis took for granted that woods in springtime saw the primrose, then the bluebell, with here and there an orchid, our wild flowers have declined markedly for reasons to do with human interference. Visitors from the cities pick nice-looking flowers, or dig them up to plant in their gardens. Accidental introductions of deer, especially the Muntjac, graze native flowers down to nothing. Many flowers listed in field guides as common are becoming hard to find outside nature reserves.

Numbers of deer in general, including our native Roe and Fallow, are increasing (and they are spreading into the suburbs) as gamekeeping declines. Since all our large native predators like bear, wolf, lynx, wolverine have long ago been hunted to extinction, there is nothing but human hunting to control deer numbers, and current levels of hunting are insufficient. Maybe George Monbiot is right: our woods need rewilding.

 

Natural History, Philosophy

Nature’s Way: Whole Plant Works, Most Active Compound Fails: Why?

The villagers queue in a long line, a hundred or more of them, in front of the traditional healer’s hut in the south of Mali. It is the rainy season, and nearly all of them have malaria.

Chief Tiemoko Bengaly learnt traditional medicine from his grandfather. Perhaps soon nobody will learn traditional African medicine any more, as modern medicine arrives, along with manufactured Chinese herbal medicines.

Bengaly hands out dried Mexican prickly poppy, Argemone mexicana, tells his patients to drink as much tea made from the plant as they can for a week. The parts of the plant have different uses, as it contains powerful toxic alkaloids; the seeds are dangerously poisonous.

Mexican prickly poppy, Argemone mexicana.
Mexican prickly poppy, Argemone mexicana.

As Brendan Borrell reports in the June 2014 issue of Scientific American (pages 49-53), the results were dramatic: 89% of the patients recovered from their malaria, compared to 95% for the current best treatment for the difficult disease, Artemisinin-Combination Therapies or ACT.  The trial was done in 2010 by Dr Bertrand Graz and Dr Merlin Willcox, and their approach was highly unconventional.

ACT consists of a drug obtained from another plant, sweet wormwood, Artemisia annua, discovered by testing plants used in Chinese herbal medicine, in combination with one or more of the many other drugs used against malaria, but which the malaria parasite has invariably developed resistance to over the years. Thus it has come about that ACT has become the last best hope against a slippery, shape-shifting parasite that has defied half a century of work by the world’s biggest drug companies and medical research foundations. All attempts at an anti-malaria vaccine have foundered on the parasite’s ability to change its biochemical spots, while all the drugs have similarly started to fail as the parasite (actually several related species, causing different malarias) becomes resistant, finding ways to continue growing in the presence of chemicals designed specifically to target vital parts of its metabolism.

One of the most remarkable things about the success in Mali – apart, that is, from its very low cost compared to traditional drug discovery, and its use of ethnobotany and a retrospective treatment outcome (RTO) study rather than a double-blind controlled clinical trial (all remarkable features of the work), was this: if the plant had been tested the conventional (I nearly said ‘traditional’) Western way, it would have failed.

The conventional Western approach would have isolated each compound that had any pharmacological activity – in other words, that did anything useful against malaria – and then tested it, alone, “in vitro” (in a test tube) to see how well it worked. It would then pick the most effective one, and try it against malaria in mice, and if that worked well and safely, then try it against malaria in humans.

The most effective substance in Argemone is berberine, and it fails against the malaria parasite. But the whole plant, as administered by healers like Bengaly in Mali, is life-saving.

Somehow, observational study in the style of ethnobotany succeeded where conventional Western medicine’s protocols for drug discovery – clinical trials and all the other paraphernalia for bioprospecting and pharmaceutical research (a jaw-cracking combination of long words derived from Latin and Greek) – would have (or actually) failed.

There is something both humbling and inspiring about this. We humans come from an incredibly clever but stupid species. Alexander Pope had it right:

 Born but to die, and reas’ning but to err;
Whether he thinks to little, or too much;
Chaos of Thought and Passion, all confus’d;
Still by himself, abus’d or disabus’d;
Created half to rise and half to fall;
Great Lord of all things, yet a prey to all,
Sole judge of truth, in endless error hurl’d;
The glory, jest and riddle of the world.

Translated, we might read Pope to say “You do your science by analysis, which is hugely effective, but it leaves you prone to endless error, for you are ignoring all the subtle side effects, interactions and combinations of effects that together make up almost everything that is worth having in the world.” Science is not wrong – it is a marvellously precise application of common sense (try whatever it is with the factor X and without, and see what difference factor X makes) – but the world is such a complex place, and the combinations of X and Y and Z and A and B and C are so many, that it will take forever to analyse everything.

In that case, integrated approaches such as traditional herbal medicine, even if they are often somewhat ignorant and wrong in places, have something important to offer. But like many other things that we are accidentally wiping out, like thousands of species of plant and animal in rainforest, ocean, mountain, grassland and marsh, we’d better be quick to study herbal medicine before it vanishes from the face of the earth for ever.

Conservation, Environment, Natural History, Nature Reserves

Gypsy Moth plague

The Gypsy Moth, Lymantria dispar, is  a notifiable pest listed by DEFRA, or at least it was when that document was published back in 1997. The insect was announced to be “a serious pest of trees and shrubs” and nurserymen and landholders were required to notify DEFRA or the PHSI HQ immediately.

Gypsy Moth caterpillar on birch trunk
Gypsy Moth caterpillar on birch trunk: blue warts at front, red warts at back. The black-and-white pattern may also be aposematic

It has arrived in the Gunnersbury Triangle with the hairy dark caterpillar larvae with blue and red warts on their backs all over some Birch trees. The infestation is rapidly defoliating them, and causing substantial damage to some Oaks too.

Lymantria means ‘destroyer’, quite a well-named genus. The caterpillars are aposematic, their hairs and bright coloration warning off predators; the hairs are irritant, containing diterpenes, complex organic ring compounds found in wood and plant resins for defence against microbes and fungi, and retained by the caterpillars for defence against predators.

It will be interesting to see how the trees cope. Oaks can generally recover even when thoroughly defoliated; the Birches may suffer more. People can hardly use pesticides in the nature reserve, even given the means to spray whole trees safely, but biological controls are imaginable. The caterpillars are parasitised by Ichneumon flies, which may well be keeping Gypsy Moths under some sort of control in Europe. There were no controls in place to halt the spread of Gypsy Moth in America, however, where the pest was accidentally introduced in 1869 from Europe by the amateur entomologist Étienne Léopold Trouvelot. He was hoping to cross-breed them with silkworms to improve their disease resistance; he is remembered instead for starting a disastrous continent-wide caterpillar plague which still continues. Attempts with other pest species to introduce their predators or parasites have often proved unsuccessful and sometimes disastrous in their turn.

Conservation, Natural History, Nature Reserves

Giant Ichneumon in London Reserve

A terrifying monster stalks the suburbs. Silently and with unerring accuracy, it scans the surface, using its advanced sensors to detect and identify targets buried deep below. Once a target has been located, the hunter drills down to find it, deposits the payload, and leaves in search of the next. It could be a cyber-borg or pilotless military vehicle. Actually, it’s Rhyssa persuasoria, the giant Ichneumon. And giant or not, it’s about 30mm long.

Rhyssa persuasoria, side view
Rhyssa persuasoria, side view

Rhyssa is a parasitic wasp, a solitary hunter distantly related to the social, black-and-yellow striped wasps. Her prey are the larvae of other insects which burrow in dead wood for food and safety. Only when she is above, safety below is hard to find. For Rhyssa‘s weapon is as long as her body: her ovipositor is greatly elongated into a precision instrument that can drill deeply through wood and into the body of the larva. Once there, she lays a single egg down the ovipositor tube. The egg hatches inside the still-living larva, and devours it from the inside. The larva dies (so Rhyssa is a parasitoid, not a true parasite that avoids killing its host) and a young Ichneumon emerges.

Rhyssa persuasoria dorsal view
Rhyssa persuasoria, dorsal view: in search of a host

Today at Gunnersbury Triangle we erected a new bench, to allow visitors to relax and enjoy a quiet moment in nature. It sounds a trivial task. If only. Two volunteers spent a day putting the “ready to assemble” kits together. All the supplied bolts were the wrong size, so they had to ream out all the pre-drilled holes to the larger size. Meanwhile, that day, I dug out the well-embedded MetPosts remaining from a previous bench. Then we dug 2 holes for the new bench: they promptly filled up with water, and the deeper we dug, the more the local weakly-cemented gravel (our local rock, when it isn’t sticky clay) collapsed into the hole, making it wider at the bottom. It was clearly hopeless.

So today we spent an hour prospecting for a drier place that would also be aesthetically pleasing, not harm the rare ferns nor disturb the nesting Blackcaps, and be close to an existing path. Then we started digging holes all over again. This time they didn’t fill up with water, much: just the bottom 10 cm or so. To keep the sides from crumbling, we avoided digging with spades: we lay on bin-bags, and wearing rubberised gardening gloves, scooped out handfuls of wet gravel. Then we levelled the two holes, cast a base of PostCrete in each, let it cure — at this point everybody disappeared for a cup of tea, leaving me in the wood guarding the site. I sat on a coppiced Willow trunk, and was approached by the giant Ichneumon when I least expected it. Luckily my little camera was not far away — you can readily imagine why I wouldn’t want the big camera with me while working.

The team reassembled, we gingerly lowered the bolted wooden creation into place, wedged it tight with broken bricks, and fixed it in place with plentiful PostCrete before cunningly sloping the top to shed rainwater. Needless to say, during this procedure we accumulated more and more tools all round the excavation site. If only it were as simple as drilling for an unseen caterpillar and laying an egg in it. But then, Rhyssa has the jump on us, with millions of years of evolution in her hunting technique.