Sunday, 8 June 2014

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.




4 comments:

Martin Parr said...

Good work Lucy - and cheers for the name check, I have learnt some more about tortoise beetles reading this!

Cheers, Martin

Boxmoor, naturally... said...

Hi Martin, it's good to hear I was able to dig up something new on the tortoise beetles :-)

Bennyboymothman said...

Stunning pictures as always Lucy.
Love the Tortoise Beetle, seen a few many years ago...
I am still here, and still reading every post that you put up :) thanks for all the daytime moth records, hopefully in a few years they will create a bigger picture of what is going on, environmentally wise.
All the best
Ben

Boxmoor, naturally... said...

Thanks Ben. You're a glutton for punishment ;-)! And, I hope last night's field trip didn't finish you off after the 5am start! Take care.