Week 45: Of Beetles, Digested & Rare

A beautiful Oak at the Brickworks

Monday dawned crisp and bright, following the first real frost of the season. Mid-morning, over at the Brickworks, there were still areas untouched by the warmth of the sun, covered in frost and ice.

SE of Baker's Wood, looking north

Frosty Nettles

Shards of ice over the grass

I squelched my way around the site, coming across a few more species of fungi (including Parrot Waxcap (Hygrocybe psittacina) and Golden Waxcap (Hygrocybe chlorophana)). Green Woodpeckers (Picus viridis) were conspicuous and, as on my last visit, a group of Jays were having a hum-dinger of a fight near the entrance track. On my way round, I could hear a small gathering of Fieldfare “chacking” to one another, which I eventually spotted. Bullfinches called softly and it was lovely when a bright, red male, brilliant in the autumn sunshine, flew over my head.

Golden Waxcap (Hygrocybe chlorophana), cap diameter approx 25mm

Having had owl pellets in my freezer for months, it will probably come as no surprise that this week I had Green Woodpecker poo drying on the radiator. It wasn’t planned, honestly. I spotted a very distinctive dropping whilst walking over Dellfield and, after a little research, discovered it was Green Woodpecker poo and that if I found a dry specimen, I’d be able to see that it was packed full of the remains of ants. Well, not one to be put off by the fact that everything was sopping wet from a day’s rain on Sunday, I returned prepared: I bagged up some prime ‘pecker poo and brought it home to dry out.

Wet ‘pecker poo in situ: 35mm long, 6mm diameter

I am mildly reassured that Chris Packham is a fan of Green Woodpecker poo and wrote, “[p]erhaps my favourite bird poo (and I'm sure many other people's too) is produced by the green woodpecker. Again cylindrical, it can be found on short grassy areas where the birds have been foraging. It is about 6-8mm in diameter and somewhere between 25-35mm in length. Its outer skin is white and the interior, visible at either end, is tan brown and roughly textured, so it can look a bit like a crumpled length of a cigarette.

The real joy of woodpecker poo, however, is picking up a dry length and squashing it in the palm of your hand as this reveals the contents as the bodies of countless ants which the bird had eaten, lots of tiny legs and heads and abdomens. Superb.”

Obviously, once the poo had dried out, I was expecting it to crumble into a mass of minute ant bodies and limbs. In fact, it appeared that this particular ‘pecker had been feasting on a smorgasbord of tiny beetles! If I had more time and patience, it is probably possible to identify a few of them from their remains. There are definitely a variety of Weevil carcasses and I did spy the elytra (outer casing) of a 14-spot Ladybird, which was surprising, given how distasteful they are meant to be to birds. Anyway, feel free to let me know in the comments if you can ID any more of them - I’d be interested to hear.

Dried Green Woodpecker poo, split in two. Diameter 6mm

Closer views of crumbled Green Woodpecker poo (scale in mm)

Whilst we’re on the subject of Beetles, the Trust had some very encouraging news last week from Martin Parr (Conservation Manager at Maple Lodge). Earlier this year, Martin had done some informal survey work at the Trust’s Brickworks and Gadespring Cress Beds sites. At the latter, he'd photographed some Bloody-nosed Beetle larvae but didn’t think too much of it until he read Trevor James’ beetle report in the Hertfordshire Naturalist 2014, which contained the following entry:-

"Timarcha tenebricosa Bloody-nosed Beetle. This conspicuous beetle was found on the towpath at Boxmoor, 12th August 2011 D.Hodges. A welcome record of a species that is strangely rare in our county, although its food plant, Cleavers Galium aparine, could not be more common."

Martin got in touch with Trevor and it transpires that the Box Moor Trust’s Gadespring Cress Beds site has the only known colony of this beetle in Hertfordshire! It’s a fantastic record and, thanks to Martin, the site can now be managed in such a way as to enable this rare Hertfordshire Beetle to continue to thrive. If, like me, you're wondering why it's called Bloody-nosed, the answer is that its defence mechanism is to secrete a blood-red liquid from its mouth which irritates the mouth of mammal predators. So, there we go!

Thank you Martin for sharing your time and expertise with the Trust (and me!) and thanks too for providing the information and photographs.

Bloody-nosed Beetle larva (Timarcha tenebricosa)

Bloody-nosed Beetle larva (Timarcha tenebricosa)

I'll finish with a couple of shots of the Dellfield Oak.

Taken at 14:40 on Monday, just before Dellfield went into complete shadow, as the sun disappeared behind the ridge of Westbrook Hay

Week 20, Surprises: The Skipper & The Tortoise

It really doesn’t have the same ring to it as “The Hare and the Tortoise” does it, but I didn’t want to get you here under false pretences. A few nice surprises yesterday, which deserve a mention, mean a hurried Sunday evening post is in order.

Saturday, I braced myself for torrential rain, thunder, lightening, and the apocalypse. However, by midday, all the drama had passed and it was warm, dry and sunny. I headed to Dellfield early evening as there is a particular scene I want to photograph. More on that another time, though. Anyway, as I climbed the path through Dellfield, a bug flew in front of me and landed in the grass to my right. Taking a closer look, it was a Common Green Shieldbug (Palomena prasina) (of week 16 fame) but what was more exciting was the Tortoise Beetle on leaves just behind it. This is another invertebrate group (or genus, the Cassida genus, to be precise) that Martin Parr introduced to me. There doesn’t seem to be a great deal of specific information about them on the internet but, as far as I can make out, they feed on the surface of leaves (specific plants for specific species) and, like tortoises, when threatened, they can pull in there antennae and legs and drop their dome-like carapace so that it is flush with the leaf. Great camouflage and good protection. 

From what I’ve read, determining species can be quite difficult, even with a photograph. However, it’s likely that the Tortoise Beetle I found yesterday was Cassida vibex, which feeds mainly on Thistles and Knapweeds. It seems to have a south-easterly UK distribution (rare or scarce beyond this region). And, it’s another tiny little creature, just 7mm long. (….Oh, ignore the Large Skipper for the moment)

Tortoise Beetle (Cassida vibex)

Large Skipper (Ochlodes sylvanus)

My first encounter with a Tortoise Beetle was last month at the Brickworks. I had joined Martin for an afternoon of surveying and he came across what we later identified as a Thistle Tortoise Beetle (Cassida rubiginosa) (not to be confused with the thistle eating Cassida vibex!). The rusty brown “triangle” at the front of the wing cases distinguishes it from the Green Tortoise Beetle (Cassida viridis).

     Thistle Tortoise Beetle (Cassida rubiginosa) [16 May 2014]

The “rubiginosa” of its name “refers to the beetle's ability to produce a red liquid from [its] head”! I’m not sure I fancy seeing that but good to know if it happens in the field and you’re after an ID! This species feeds on Creeping Thistle (Cirsium arvense) and, according to NatureSpot, “has the most interesting larvae and pupae. The larvae have twin tail-spikes and these are sometimes used to carry dead skins and droppings in a kind of parasol [nice!]. The spikes are retained by the pupa and these are flicked forward if it is disturbed.” Weird eh! So, there were are. A whirl-wind introduction to the genus Cassida, the Tortoise Beetles. Hopefully, I’ll come across a few more over the coming months.

Obviously, the other colourful find yesterday was a Large Skipper butterfly (Ochlodes sylvanus) (actually there were two) on Bovingdon Reach. And, on the pond on Preston Hill, I watched 3 male Broad-bodied Chasers achieving olympic standard “chasing” around the water. One, with a broken wing, eventually perched on a twig close by, giving me a chance for photographs (below). Finally, as I was walking from the pond towards Hay Wood, I heard the most peculiar sound. A friend had recently described to me the “call” of a female Cuckoo and, I can only conclude that that is what I heard. It was a kind of subdued, hallow, rich random burbling, coming from the tree tops. Unfortunately, it was too distant for the mic on my camera to register otherwise I would have recorded it. Ultimately, the source will remain a mystery but it would be nice to think that a female Cuckoo is around and the species has bred this year in Hay Wood.