Larva palaver

Identifying caterpillars shouldn't be too difficult should it -especially the big flashy ones.

When my daughter found this one strolling across a grassy footpath on the Bamburgh cliff top I took a quick photo with the plan to sort it out definitively back home.

The first two field guides I tried were inconclusive, with none of the illustrations matching this one exactly or with illustrations so small that the detail could not be made out.  This included, disappointingly,  the Collins Field Guide to Caterpillars of Butterflies and Moths in Britain and Europe.  The most helpful has been my old favourite, Margaret Brooks and Charles Knight's 'Complete Guide to British Butterflies' from 1982.

The trouble is that caterpillars can be a bit of a bother. They have to moult to grow, averaging four or sometimes five changes before full size. In some species not only does the look of the caterpillar change significantly at each moult but even the same instars of different individual caterpillars show variations in colour and pattern.

The easy bit is that spiny larvae are most likely to be members of the Nymphalidae family.
 

Given that this is Northumberland and we have a smaller range of species compared to the warmer southern climes, the realistic options are limited.  Although this one does not exactly fit any of the descriptions or photos I have found, on balance it's the red admiral that gets my vote but I wish I could say that with 100% conviction.    Any offers?

Harebells, re-visited

Although I have waxed on about harebells before, I need little excuse to do so again. Walking one of the footpaths that cross Bamburgh golf course the other day I came across a small patch with pure white flowers in the rank rough between the fertilised fairways.

So, (he says, looking in the general direction of Greenfingers....), is this unusual? Is it a variation in the wild harebell or might these be a different species or variety given that this is a heavily managed golf course?

Grabbed by the Barnacles

After a holiday pounding the London streets with the family, what better way to unwind than to ponder the barnacle.

From a distance, the intertidal rocks to the north of Bamburgh are a lovely caramel colour but get close up and you see that the rock is in fact almost black. The caramel effect is made by barnacles - millions upon millions of them. What particularly grabbed me though, is that when you look more closely, it is mainly the upper parts of the bigger barnacles that have the colouration.

The bases of the shell plates are white, as are the smaller ones. Why?

I have to say that I have struggled to find a definitive answer but a passing reference (in a google hit that frustratingly wouldn't actually open) hinted at colouration due to 'algal infection'. If this is true, why white at the base and why only the larger barnacles?

Here's my theory then, for what its worth. As a barnacle grows so the external shell plates have to enlarge to accommodate the bigger beast inside. In this species, new shell material is secreted along the base of each shell-plate. Perhaps then, the new stuff stays white for a while until the algal colouration takes effect, by which time its been pushed further up the shell by more new (and white) growth below. Hey presto, white bottoms and caramel tops. If this is true then the young barnacles -the smaller ones- should be all white (they are - see photo) and a barnacle that has finished growing should be all caramel (see the larger barnacle at the bottom of the photo). I rest my case.

This species is Semibalanus balanoides, the most widespread and successful intertidal barnacle in the British Isles. Until the mid 70s it was known as Balanus balanoides until cut down to size and renamed by the barnacle boffins.

Stood on and ignored by many a beach visitor it may be, but I reckon that any creature that spends the first part of its life floating about as a piece of plankton, then one day sticks itself by the head to a rock, turns itself into a hermaphrodite crustacean in a rock-hard shell stuck down with one of the toughest natural adhesives there is, catches its dinner with its feet and has, proportionately, one of the largest male appendages in the animal kingdom (which incidentally drops off and then re-grows each year) is worthy of a bit more attention than that.....

Show us your legs

The brain of a fly isn't much but there must be something going on in there. Yet even in these internet days its really difficult to find out much about the behaviour of St Mark's Fly. Bamburgh dunes were full of these black dangley-legged things today. Facts established: so called as they tend to emerge on St Marks day (April 25th); males have larger eyes than females (so that's a male in the top photo); males do an up and down flight to attract females.

Unaswered questions:-

1. Is it just the males that dangle their legs in flight?
2. If so, does the length of their dangling bits determine their mating success?
3. If one emerged 2 days early would it be St George's Fly?