Category Archives: Natural History

Dragonfly Day at Thursley Common

Keeled Skimmers - male guarding, female laying
Keeled Skimmers – male guarding, female laying

It was suddenly summer again this morning, so I packed cameras, binoculars and a sandwich and went down to Thursley in glittering sunshine. This photo perhaps catches something of the dazzle and sparkle of the bog pools and their shimmering guardians: a pair of Keeled Skimmers (Orthetrum coerulescens) are flying over the water; she is darting down to lay eggs, he is hovering above, guarding her from other males. Their wings sparkle and flash, and it is amazingly difficult to follow, frame, focus and shoot fast enough to get anything like a decent picture. But I rather like the motion blur in this one, and if it’s not perfectly in focus, you know why. I hope you like it too.

Emerald Damselfly
Emerald Damselfly

I was pleased, too, with this shot of an Emerald Damselfly, the sparkling water behind it forming a pattern of pleasantly out-of-focus circles.

Small Red Damselflies in Wheel
Small Red Damselflies in Wheel

There were quite a few Small Red Damselflies about, mostly single but a few egg-laying pairs; and a modest number of blues, most likely Azures.

Apart from the hundreds of Keeled Skimmers, other dragonflies included Common Darter, Black Darter (I only saw a few females today), Black-Tailed Skimmer (just one), and Southern Hawker.

Large Skipper on Bog-Cotton
Large Skipper on Bog-Cotton

We saw few butterflies apart from Large Skippers which bustled about flowers near the boardwalk, and little Gatekeepers (I do mean they were smaller than usual) … until we arrived on the amazing Parish Meadow that was once a dump for emptying cesspits. Now it has an ecology strikingly unlike the rest of Thursley Common.

Centaury on Parish Meadow
Centaury on Parish Meadow

The meadow was full of Meadow Browns, Graylings (mating), Ringlets, Essex Skippers, a Brimstone, Large and Small Whites, and … a Purple Hairstreak (about the Oak trees). The rabbit-bitten pasture, dotted with little flower-stalks of Centaury,  was thick with Ragwort, which in turn was richly covered with Cantharid beetles, solitary bees, wasps, and hoverflies and other Diptera. We put up a Silver Y moth which obligingly landed in front of us and perched in the open. We found the traces of a Green Woodpecker killed by a Sparrowhawk; but happily saw a live one in the Oaks nearby.

Cantharid Beetles Rhagonycha fulva mating on Ragwort
Cantharid Beetles Rhagonycha fulva mating on Ragwort
Silver Y Moth
Silver Y Moth
Sparrowhawk Kill - this Green Woodpecker's flying days are over
Sparrowhawk Kill – this Green Woodpecker’s flying days are over

The boardwalks were busy with Lizards and Skimmers sunning themselves.

Lizard on boardwalk
Lizard on boardwalk

We met a local group of birders,  complete with masses of tripods, telescopes and cameras, and asked if they were looking at the Stonechats. No, they replied, the Hobbies, there are three. We looked up, and sure enough there were three raptors. But in our binoculars, they turned out to be a Kestrel, a Hobby, and a Red Kite! Perhaps there were some more Hobbies somewhere else.

A little way further, absent the birders, we found a dead tree with some juvenile birds perched about it, and a lot of twittering. Yeah, a typical Chiswick Cafe. Some of them were young Redstarts; the others, young Stonechats: pretty confusing. But the Redstarts flew up into a Pine tree – not a Stonechatty thing to do – and sure enough, there was an adult Redstart on a lower branch, plain to see. And a Stonechat adult rasped out its grating call over to the right.

In a group of tall Oaks, we sat and ate a sandwich; and a Spotted Flycatcher flew across and perched on a high dead branch. It spent five minutes looking about, twisting its neck remarkably, but making no sallies. When I was a boy I saw them in the garden every summer; now they’re really something special, like, er, Starlings and House Sparrows.

Meadow Grasshopper
Meadow Grasshopper

The sandy heath paths were full of little holes dug by Ammophila Sand-Wasps, and others made by Philanthus Bee-Wolves (or Bee-Killer Wasps). Both are called digger wasps (“Sphecidae”) in most books, and it’s certainly a good name, but the family has been split up, so Philanthus is now in the Crabronidae, which contains most of the old “Sphecidae” (we’ll have to say sensu lato for this); the new Sphecidae (sensu stricto) only contains what used to be the Sphecinae, which includes Ammophila. Rich scope for confusion.  Sphex is the ancient Greek word for wasp, and it’s interesting that Linnaeus chose this word for a digger wasp rather than the social wasps, which have the Latin name Vespa for the hornet, and Vespula, little wasp, for common wasps.

Bee-Wolf (Bee-Killer Wasp Philanthus triangulum)
Bee-Wolf (Bee-Killer Wasp Philanthus triangulum)
Bee-Wolf digging burrow. She will catch a bee and use it to provision her nest.
Bee-Wolf carrying a bee into her burrow to provision her nest.
Sand-Wasp Ammophila pubescens
Sand-Wasp Ammophila pubescens. She too digs a burrow which she provisions with a caterpillar or two. The sand is dotted with angular lumps of iron pan.

Out of a low bush of willow and gorse right beside a boardwalk came a strange, quiet but insistent squawky chatter of alarm. Peering in between the branches, a small slim dark bird with a long dark tail could be seen hopping about anxiously: a Dartford Warbler. It was extraordinary to be within a few feet of this shy, rare and retiring bird, and watching it for several minutes. There are actually quite a few on the heaths of Surrey and the south coast, but they’re never easy to see—most of my views have been of disappearing rear ends, diving into gorse bushes.

Clouds of Butterflies … in London

Essex Skipper on Ragwort
Essex Skipper on Ragwort

Well, what an exciting day in nature. In London, too. The meadows are now as dry as we’ve ever seen them; and they’re full of butterflies. The Small Skippers have flown; in their place are plenty of Essex Skippers, on an increasing amount of Ragwort.

An obliging Gatekeeper, wings open
An obliging Gatekeeper, wings open

They are accompanied by clouds of Gatekeepers: we must have seen 100 of them, with 35 counted on one leg of the Butterfly Transect alone (going along to the beehive behind the Anthill Meadow). And good numbers of Meadow Browns (a dozen or so) and Small Whites; with twenty or thirty Holly Blues, they were high in the woods, visiting leaves, even on the ground.

Male Sparrowhawk
Male Sparrowhawk

A male Sparrowhawk perched on a dead branch above the pond boardwalk.

Oak bush dying of drought
Oak bush dying of drought

Signs of drought were everywhere: the pond is really low, but the brief rains of the last few days have brought levels back up a little. We spend a while giving 7 barrowloads of water to the planted birches on the embankment, and even rescued a few small oaks that were really suffering. The holm oaks, from the Mediterranean maquis, however looked perfectly comfortable: presumably with their waxy leaves and closed stomata, they are barely growing in the dry season.

Girl power: fixing a batten for trellis on green hut
Girl power: fixing a batten for trellis on green hut

We fixed up a trellis on battens bolted to the extremely hard steel of the green hut; it took forever to pierce the metal, but after that it was easy to do up the bolts and screw the trellis to the battens.

Yes! We saw a Purple Hairstreak!
Yes! We saw a Purple Hairstreak!

And yes, the butterfly transect was crowned by a confirmed sighting of an insect we’d felt sure must be here: a Purple Hairstreak. One sat on a low-hanging Oak leaf for us to check with binoculars and shaky camera. The streaked wings with their tiny tails could not be mistaken. The conservation officer was … visibly pleased. We also saw what seems to have been a Beautiful Carpet Moth – again, the photo was distant but we all saw it with binoculars.

It was hot and humid, and we worked quite hard, but it was a beautiful and memorable day.

Damsel Ant Mimic Bug Himacerus mirmicoides in Gunnersbury Triangle

Ant-mimic bug, Myrmecoris gracilis on Ragwort
Ant-mimic bug, Himacerus mirmicoides on Ragwort

Here’s a bug that avoids being eaten by looking quite enough like an ant to fool a variety of predators.  Its name, mirmicoides, means ant-like. Its naturally thick body is made to appear to have a typical ant “waist” with a judicious bit of white camouflage.

Ant-mimic predatory bug, Myrmecoris gracilis, dorsal view, on Ragwort
Ant-mimic predatory bug,  Himacerus mirmicoides, dorsal view, on Ragwort

Certainly an interesting “bug” to find. (It’s a true bug, family  Nabidae, the damsel bugs, in the Hemiptera.)

Ant-mimic predatory bug, Myrmecoris gracilis, on Yarrow
On Yarrow

The long and distinctly un-antlike rostrum is held under the head, so predators presumably don’t notice it much. The antennae are similarly much too long to be an ant’s.

Ichneumon Attacks Cinnabar Caterpillar; Small & Essex Skippers

Ichneumon Wasp and Cinnabar larva, just after the 'sting'
Ichneumon Wasp and Cinnabar larva, just after the ‘sting’

Well, what a piece of luck. I was just inspecting the ragwort where the Cinnabar caterpillars were clustered (by the rail of the Anthill Meadow), and had seen they had grown, and had dispersed from one stalk to three or four — when I saw an Ichneumon approach with the usual dancing flight. Grabbing the camera, I took three photographs, of which the above is the last, and I think the prettiest.

Ichneumon Wasp pointing ovipositor at Cinnabar larva
Ichneumon Wasp pointing ovipositor at Cinnabar larva

This is the second photo: the wasp has her abdomen curled beneath her body, towards her prey (ok, host, she’s a parasitoid).

Ichneumon attacking Cinnabar larva
Ichneumon attacking Cinnabar larva

And this is actually the first photo, the wasp very close to the caterpillar, her ovipositor sharply folded under her thorax: the caterpillar has just twitched sharply, presumably on being ‘stung’ with an egg now fatally implanted in its body. The cinnabar is aposematic, full of bitter and poisonous chemicals, which don’t protect it against this sort of attack, evidently.

Down by the pond there were plenty of Azure damselflies, one Common Bluetail, and some really tiny newly-metamorphosed froglings hopping about in the mud. A Small Skipper perched obligingly on a Yellow Iris leaf, not far from a plump Iris Sawfly larva.

Small Skipper on Yellow Iris leaf
Small Skipper on Yellow Iris leaf

Down at the Picnic Meadow, ignoring a picnic and dropped bicycle in the entirely dry brown grass, an Essex Skipper visited some Bramble flowers. It’s just like the Small Skipper, but without the orange on the antennae.  A Meadow Brown sat in the grass.

Essex Skipper on Bramble flower picnic meadow
Essex Skipper on Bramble flower picnic meadow

In the woods, a Holly Blue flew high, near a Holly tree. A Small White completed the butterfly tally for the walk.

Wetland Centre Bugs

Dabchick in glorious dress, with wiggly reflections
Dabchick, with wiggly reflections

I wasn’t really birding but it was nice to see a little cloud of House Martins flycatching, and a richly dressed Dabchick diving for food.

Foamy wisps of scented Meadowsweet flowers were visited by honeybees; a Strangalia maculata longhorn beetle (it doesn’t have an English name, but it’s not the one usually called Wasp Beetle) clambered slowly over the flowerheads. It looks reasonably wasplike, if not terribly convincingly; it would be interesting to know if it is itself foul-tasting and hence actually aposematic, or just hitching a free ride through Batesian mimicry.

Strangalia maculata, a waspish longhorn beetle
Strangalia maculata, a waspish longhorn beetle, on Meadowsweet
Bee on Bramble flower
Bee on Bramble flower

The Wetland Centre was very sunny, a little windy for butterflies (only Small Skipper, Red Admiral and Green-Veined White) but with the bees buzzing around the many flowers, very attractive. Several Orchids were in bloom, including purple and pyramidal. Even the different bindweeds looked wonderful. A pair of Mute Swans rested calmly with a cygnet or two at the bronze feet of Sir Peter Scott.

A teneral (new) darter
A teneral (new) darter

The dragonflies included one Black-tailed Skimmer, sunning itself on a “wildside” path; several blue hawkers, probably Hairy Dragonflies; an Emperor; a teneral darter, probably Common Darter; masses of blue damselflies – all the ones I managed to check were Azure Damselfly; and a few Common Bluetail damselflies.

Immature male Common Bluetail damselfly

Immature male Common Bluetail damselfly

 

Spanish Summer … in Chiswick

Azure Damselfly Wheel
Azure Damselfly Wheel

The pond is really low in the heat (and the grass is brown and crisp, and Birch trees large and small are dying). There are Large Red, Azure and Bluetail damselflies urgently laying eggs; this pair of Azures was in the incredibly complicated mating posture that we call the Heart or Wheel, with secondary genitalia locked on in preparation for transfer of the spermatophore; then the female does her thing with sperm storage. Bizarre.

Red Admiral - battered but still flying
Red Admiral – battered but still flying

If there’s an insect equivalent of a World War II Hurricane landing safely with most of its tailplane, rudder, and wings shot away, this battered but defiant Red Admiral must be it. I saw the odd outline and thought “Comma?” – then I saw the colours and thought “Hot weather, beaten-up butterfly, Painted Lady”; then it landed and I realized what it was.

Heat. It’s apparently the hottest day in England for nine years: right now it’s 33ºC here, and remarkably sticky.

Cinnabar Moth Caterpillars on Ragwort
Cinnabar Moth Caterpillars on Ragwort

Among the dry grass are an increasing number of Ragwort plants; at the moment, having seen just one Cinnabar moth flying briefly, there is also just one plant covered in Cinnabar caterpillars. They are aposematic: brightly coloured black and orange, warning, like wasps and bees, of their poisonous cocktail of chemicals picked up from their food plant. They seem to grow in numbers until they devastate the Ragwort population, which then crashes … which wipes out the Cinnabar moth, until a new outbreak of Ragwort restarts the cycle. It seems to me the nearest thing to the Lotka-Volterra model ever, given that the model basically predicts wild swings in population of “predator” and “prey”. For lynx and snowshoe hares it’s a wildly wrong model; for moths and Ragwort, maybe there’s something in it.

Making croc coffins (plant boxes) for the car park
Making croc coffins (plant boxes) for the car park

We spent some happy hours cutting up a lot of wood to make two large “planters” to disguise the green metal box of a shed in the car park. The plants will need constant watering, which sounds a bit of a problem, but maybe for annuals it’ll do fine. We nicknamed the planters “crocodile coffins” as they are the size of young crocs and perfect for their funerals, if crocs need ceremonies.

Yesterday evening we had a fine view of the conjunction of Venus and Jupiter in the western sky, Venus an elegant bright crescent (evening star) on our side of the sun, Jupiter a smaller and dimmer star, visibly a complete disk, far away from us of course on the other side of the sun. The 80mm birdwatching telescope did a good job; of course it would be lovely to have a big astronomical telescope to get a bigger view.

This Week’s Insects at Gunnersbury Triangle

Comma butterfly
Comma butterfly

Comma, Red Admiral, Small White, Meadow Brown, Holly Blue, Speckled Wood butterflies this week. A Cinnabar Moth, the first of the year, flew over the bank near a patch of Ragwort, the food plant of its caterpillars. Let’s hope she laid some eggs.

Tree Bumblebee Bombus hypnorum
Tree Bumblebee Bombus hypnorum
Macrophya Sawflies mating on Hogweed
Macrophya Sawflies mating on Hogweed
Bluetail Damselfly on Iris
Bluetail Damselfly on Iris

The first Bluetail Damselfly appeared today; Azure and Large Red Damselflies still about.

Honey Bee on Bramble flower
Honey Bee on Bramble flower

Small Skipper, Migrant Hawker and more at Gunnersbury Triangle

We had a lovely day down the reserve in the warm sunshine with a gentle breeze. We dug out an unwanted post with extreme use of pickaxe, crowbar and shovel, and thus refreshed did the butterfly transect. It found a Red Admiral, some Speckled Woods, wonder of wonders a Small Skipper (the second Skipper species this week), a Meadow Brown (not common here), and a Green-Veined White. Not a bad haul. And a lot of Peacock caterpillars, if those count!

Small Skipper
Small Skipper
Wasp Beetle
Wasp Beetle (Strangalia maculata)
Ladybird Larva
Ladybird Larva
Migrant Hawker
Migrant Hawker
Two-Spot Ladybird
Two-Spot Ladybird
Eat me if you dare - Aposematic caterpillars of Peacock Butterfly
Eat me if you dare – Aposematic caterpillars of Peacock Butterfly
Neuropteran (Lacewing) larva
Neuropteran (Lacewing) larva – note the forceps-like mandibles
'Marmalade' Hoverfly dorsal view
Macrophya sawfly dorsal view

Hot Summer’s Day Insects

Rose Chafer Beetle on Hogweed, dorsal view
Rose Chafer Beetle on Hogweed, dorsal view
amazing fly red abdomen black spots
amazing fly red abdomen black spots

On this lovely hot day, we tried to work, hammering in pegs to fix path edging poles. When we were all a bit dizzy from the heat and effort, we gave up swinging the sledgehammer and had a tea in the hut. Then we did a butterfly transect, which in the absence of anything but Speckled Woods, turned into a nature walk as we photographed all the other interesting insects. The Rose Chafer (on hogweed) is worth looking at full-screen as it’s very pretty.

A brown Shield Bug cf Coreus on Hogweed
A brown Shield Bug cf Coreus
Hoverfly Leuzozona leucorum
Hoverfly Leucozona leucorum
Array of Aphids on translucent Sycamore leaves
Array of Aphids on translucent Sycamore leaves

These aphids looked amazing with the sunlight streaming through the leaves; the leaves below were spattered with sticky sugar dropped by the aphids.

There was a beautiful Click Beetle too (like Athous haemorrhoidalis) but I didn’t photograph it as we were having too much fun making it go click and jump out of our hands.

Azure pair over Large Red Damselfly
Azure pair over Large Red Damselfly

See the Red damselfly? Look up: there’s a pair of Azure damselflies hovering above.  Well worth viewing full screen.

Great Tit feeding brood in Nest Box 10
Great Tit feeding brood in Nest Box 10

We were pleased (and somewhat surprised) to find a family of Great Tits in box 10, right beside the path, and not terribly high up either, but it was an old and presumably proven nest-site, and so it has proven again this year. I got a blurry photo of one of the proud parents entering the hole, which I had repaired with some aluminium sheet this winter.

Ovipositing pair of Azure Damselflies
Ovipositing pair of Azure Damselflies; female is the green morph

I was very pleased with this photo, with its surreal light and bubbles. I’ve not remarked the green female morph before: most Azure females seem to be a paler, more lime-green form.

China Mark Moth laying eggs on pond weeds
Brown China Mark Moth laying eggs on pondweeds

This last photo (taken at quite a distance) shows something very curious: the Brown China Mark, a micro moth that lays its eggs on pondweeds, scurrying over the surface of the water searching for suitable ovipositing sites. In the dazzling light, she was far more reflective than anything else, and I had to turn the exposure down two whole stops to get her about right. The larva is aquatic, feeding on pondweeds.

Not pictured: sawflies; a swift Ichneumon beside the pond (without a long ovipositor, but with a clearly clubbed abdomen); many bumblebees and striped hoverflies. Nests of Peacock butterfly caterpillars too.