Saturday, 30 August 2014

Week 32: Brickworks Brown Argus Colony

I wasn’t expecting much this week (and was actually just glad when it finally stopped raining!). Rain all day Monday. Rain most of Tuesday and fairly cool, breezy, cloudy days following. I spent a little time at Roughdown Common on Wednesday, trying to relocate or add a Chalkhill Blue (Polyommatus coridon) to the Brown Argus (Aricia agestis) of last week. I dread to think how many Common Blue butterflies (Polyommatus icarus) I chased down only to be disappointed. I couldn’t find the Brown Argus again nor add anything else to it.

Thursday, I thought I’d give Bovingdon Brickworks a try. Having spent a couple of hours hunting Brown Argus the previous day, I couldn’t quite believe my eyes when, within a few minutes of arriving, I’d found one at the Brickworks. One turned into two, which turned into three, which continued to rise until I was trying to follow/check/photograph at least six different butterflies. The conditions were such that they weren’t settling for long and so my best bet for identifying each individual was to photograph them the moment they stopped moving and then analyse the shots when I got home. Most of the specimens were quite worn so I was really chuffed to find one which was in good condition.

Bown Argus (Aricia agestis) [Specimen 1]


Below are the other five individuals that I was able to track down (with their identifying marks/damage highlighted). I know that at least a seventh got away and I wouldn’t be surprised if there were a few more besides. The fresher Specimen 1 is quite interesting and it does make me wonder if it is from a second brood, from on site. Either way, it is an extremely scarce species locally, not reported at this site previously and I am very much hoping that this small colony is a sign of things to come. It is located in the area of the Brickworks that I only discovered recently (see modified Buddleja location map here).

    Specimen 2
    Specimen 3
    Specimen 4

    Specimen 3 & 4 (Male & Female)
    Specimen 5
    Specimen 6


Whilst my head is full of Brown Argus and Common Blue butterflies (what a nice picture that conjures up! Butterflies for brains), I thought I’d put together a quick guide to separating the 2 species, especially the female Common Blue from the Brown Argus. The Common Blue butterfly, featured below showing the upper wings, is one I photographed alongside the Brown Argus on Thursday. It’s very worn but you can just make out the remnants of blue scales and, of course, the lack of dark spot in the forewing. The dark forewing spots alone aren’t diagnostic for Brown Argus so it’s important to note an absence of blue scales and/or the underside spot arrangement.



Ok, enough of Brown Arguses! What else? As I walked through the woods, on my way to the rest of the Brickworks, a little Nuthatch was calling from the trees and I could also hear at least 2 pairs of Bullfinches. The Emporer dragonfly that’s been patrolling that area for the past few weeks flew in close to take another look at me. Elsewhere, the number of Speckled Woods (Pararge aegeria) on site is impressive. There must be at least 30 individuals. I was also excited to find 5 Red Admiral butterflies (Vanessa atalanta), all in excellent condition. I’m guessing these are second brood rather than the original migrants of early summer.



Finally, I should round things off with this week's Oak photograph. It feels rather uninspired but the light/weather/my energy etc haven't permitted anything else…

2 comments:

Martin Parr said...

Great work Lucy, an excellent ID guide and wonderful to confirm the individuals!

Boxmoor, naturally... said...

Thanks Martin. Added another 7 to the count today :-)