Week 33: Mining, Growths & Another Argus

I should probably begin by confessing that I couldn’t resist another visit to the Brown Argus (Aricia agestis) colony. However, for those less inclined to pedantically scrutinise the wear patterns of battered butterflies, I’ll leave the results of that until the end. My visits this week to the rest of the Trust’s land have been very brief, which is a shame given the calm, warm conditions.

The Horse Chestnut trees (Aesculus hippocastanum) are looking at their best and worst. Their best, because they are laden with Autumn fruit (aka conkers!), and their worst, because the mining moth (Cameraria ohridella) has left no leaf untouched! Incredibly, although the damage looks decidedly vicious, the health of the tree is essentially unaffected. Its leaves will return as normal next year all set for another moth infestation, I expect. The light on Wednesday evening was beautiful, giving me the opportunity to enjoy the Horse Chestnuts (and horses) on Station Moor.


Early Autumn fruits are abundant now (blackberries on Bramble, berries on Hawthorn, hips on Roses, sloes on Blackthorn, elderberries on Elder etc) and acorns aren’t the only growths on the Dellfield Oak. A fresh eruption of the fungus Laetiporus sulphureus has appeared on the trunk less than 2 metres from the ground, on the east side, in an old wound. According to the internet, it tastes like chicken, hence its common name "Chicken of the Woods". However, I have no intention of wasting a good onion on finding out if wikipedia can be trusted or not.

Another conspicuous fungus which I photographed at the Brickworks is Tar Spot (Rhytisma acerinum) on sycamore leaves. It looks a lot worse than it is and again, like the mining moth, doesn’t do significant damage to the health of the tree.

Fancy some chips with your chicken?!

Tar Spot

Ok, to my guilty pleasure, indulged on Tuesday morning when the sun shone and the breeze was barely noticeable. A family party of tiny, trilling Goldcrests were in the trees as I made my way to the south-east side of Baker’s Wood at the Brickworks. A couple of Common Darter dragonflies flitted back and forth around the path. My eyes, however, were firmly focused on spotting the Brown Argus butterflies. I promised myself I wouldn’t spend more than about half an hour at this task, especially if I kept finding specimens I’d already seen on previous visits. The results were quite interesting (what?! they were).

I refound 6 specimens, 2 from last Thursday and 4 from Sunday, which just goes to show how little the Brown Argus wanders. I also found one more new specimen to add to the tally, making a total find of 14 individuals. I've christened this one Tatty, for obvious reason. Of the 6 refound, 3 had incurred further damage or wear, demonstrating just how quickly their condition deteriorates at this stage in their lifespan, even in a matter of 48 hours.

The Brown Arguses would turn up anywhere along this path

14. Tatty

Below are comparison photographs of the 3 refound butterflies, showing the changes in their wear patterns incurred in a matter of days. The original 13 butterflies can be viewed here.

3. Left Dink. The little tear in the left forewing has caused a small portion to subsequently fall off [shown left]









11. Worn. The trailing edge of the right hindwing has been damaged [shown below]

12. Big Notch. The damage to the left hindwing has worsened and there’s also now a small notch missing from the left forewing [shown right]












I think that's probably the last of my Brown Argus spotting (that wasn't a sigh of relief I heard was it?!). Knowing for certain that there are at least 14 individuals in the Brickworks colony is satisfaction enough. The peak count at Aldbury Nowers (the species stronghold) last year was 38 in week 22 (27/08/2013). The Nowers transect recorded 80% of the total number of Brown Argus observed across the whole of Hertfordshire and Middlesex last year. A count of 14 outside of that area is certainly significant and very encouraging.

Time for this week's horse photograph

Sorry, I meant Oak photograph

Week 32, Brown Argus Extra: Who's Who!

Spurred on by the calm sunny conditions this morning, I thought I’d have another go at assessing the size of the Brown Argus (Aricia agestis) colony at Bovingdon Brickworks. It’s been something of a painstaking task but also surprisingly satisfying, especially given the results.

OK, so we have the original 6 specimens from Thursday. For ease of identifying the individuals, I've named them after their damage/appearance as best I could. The gender pronouns are randomly chosen rather than indicative of the butterflies sex.

1. Mr Perfect

2. Right Nick

3. Left Dink

4. Mr Not Bad

5. Double Damage

6. Rear Right

And, today, I added a further 7 specimens to the count, producing a total of at least 13 individuals* on site. I only re-photographed (if that’s even a word!?) one of Thursday’s specimens today.

7. Rear Left

8. Ms Subtle

9. Left Nick

10. Right Little Dinks

11. Worn

12. Big Notch

13. Worn Too

Together

Underside

To put this total of 13+ into perspective, in 2013, the total number of Brown Argus recorded at other monitored sites nearby (excluding Aldbury Nowers, Tring, which is a Brown Argus stronghold) were as follows:

Location Tring Park, Tring Miswell Lane, Tring Lakeside Nature Reserve, Finchley Heartwood Forrest, St Albans Stocker’s Lake, Rickmansworth Sherrards Park Wood, Welwyn Garden City       Roughdown Common, Hemel Hempstead Shrubhill Common, Hemel Hempstead Harpenden Common, Harpenden

Quantity      4    0    0    7    0    0    0    1    0

There are more in the one small area at Bovingdon Brickworks than at all 9 sites combined last year! Moreover, it's a species which occurs in small, compact colonies and is "not a great wanderer, only travelling a couple of hundred metres, at most, from where it emerged.” It'll be great to see how this colony develops next year.

I will try to prise myself away from Brown Argus counting next week, I promise!

*NOTE 05 Sept 2014: I found a 14th individual on the 2 Sept 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…

Week 31: Butterfly Finale & Next Gen Bugs

I had my first blog-related nightmare this week. I dreamt that I arrived at Dellfield only to discover that over night there had been a kind of landslide/sink hole catastrophe. The whole meadow had sunk by about 4 foot. The Oak and Scots Pine had been completely uprooted and lay destroyed, on their sides, as if gunned down. Part of Hay Wood had slipped down the hillside and the whole area was unrecognisable. I couldn’t quite believe what I was seeing but, with dawning realisation, I actually began to cry. I guess over the past 8 months, Dellfield, the Oak and the Pine have become like old friends. Let’s hope I’ve not been blessed with the gift of prophecy!

Monday morning, I decided I’d concentrate my efforts on Bovingdon Reach meadow at Westbrook Hay. A group of about 15 Swallows were flying less than a foot above the ground, chattering to one another and searching out insects. My car thermometer read 13 degrees Celsius so it felt a little chilly although the sun did occasionally find its way through the banks of grey cloud (see photograph above for grey cloud proof!).

My first find was an immature (mid instar) Bronze Shieldbug (Troilus luridus) on Hawthorn berries. It’s a predatory bug which feeds on other insects although the nymphs (immature stages) also feed on plants. It occurs widely across the the UK but I’m not sure how common it is in Hertfordshire. There’s one generation per year. If you're interested, you can find pictures of the adult here.

Next up was a Hairy (or Sloe) Shieldbug (Dolycoris baccarum), so called because, well, it’s covered in hairs. At around 11-12 mm in length, it's twice the size of the tiny little Woundwort Shieldbug of Week 19. “It overwinters as an adult, emerging in the spring. Larvae, which are also hairy, may be found on numerous plants, particularly those in the Rosaceae. The new generation is complete from August onwards.

"It's common and widepsread in many habitats throughout Britain, particularly hedgerows and woodland edges, becoming scarcer and mainly coastal in the north”. It was a new species to me so I was chuffed to encounter it. I'm not sure if this is a fresh adult from this year or one from a previous generation. It's also just beginning to lose its lovely purple summer colouring and adopting its duller, brown winter hues.

Hairy Shieldbug (Dolycoris baccarum)

Finally, as I made my way towards Hay Wood, I spotted a Small Heath butterfly (Coenonympha pamphilus). These seem to be very scarce locally and I think this was only my second sighting this year (the first, I think, being a fleeting view at Roughdown Common, late Spring/early Summer). Anyway, I was pleased to manage a photograph this time before I lost it again. The larval food plants are grasses, specifically Bents (various) (Agrostis spp.), Fescues (various) (Festuca spp.) and Meadow-grasses (various) (Poa spp.).

Tuesday was a little warmer and much sunnier. Further Roughdown was covered in the white frosting of Eyebright and the purple splashes of Marjoram. Common Blue butterflies aplenty. I keep hoping I’ll come across a Chalkhill Blue or some other chalk plant loving species. Roughdown Common always feels like a habitat full of promise. And….it is...

A couple of immature (late instar) Dock Bugs (Coreus marginatus) were together on a bramble leaf (photographed left), up on the south-west side of Lower Roughdown. And, after wandering the bank, bordering the A41, I eventually spotted what I suspect will be this year’s butterfly finale, a species I was extremely pleased to find and one which just goes to prove the potential of this site. A Brown Argus (Aricia agestis). Having corresponded with a couple of experienced, local butterfly recorders, it seems that the Brown Argus is another local scarcity. Two were observed in 2012 at Roughdown Common, none last year.

Colonies of Brown Argus butterflies are generally found on chalk or limestone downland, where the primary larval food plant, Common Rock-rose thrives. Adults feed on Marjoram (Origanum vulgare) as well as Ragwort (Senecio jacobaea), Thyme (Thymus polytrichus) and White Clover (Trifolium repens). Roughdown Common certainly has the habitat to support this species but it’s obviously still only 1 or 2 specimens, if we're lucky.

Butterfly Finale - Brown Argus (Aricia agestis)

Project 2014 was never meant to be a scientific monitoring or recording of species around the Box Moor Trust sites. It was much more about enjoying the land and just seeing what turned up. However, I think that the Brown Argus was the 26th species of butterfly I’ve seen on Trust land this year, which speaks volumes to the quality of the developing habitat. According to Herts and Middlesex butterfly records for 2013, there are a total of 35 possible species present across the counties. Those I've not seen at the Box Moor Trust sites this year (so far):

1. Grizzled Skipper
2. Clouded Yellow
3. Purple Hairstreak
4. White-letter Hairstreak
5. Small Blue
6. Chalkhill Blue
7. White Admiral
8. Purple Emporer
9. Dark Green Fritillary

Species I have seen at the Box Moor Trust sites this year:
(if I saw them at one site only, I’ve indicated that [BW = Bovingdon Brickworks; RD = Roughdown Common])

1. Brimstone 2. Comma 3. Small Tortoiseshell 4. Peacock 5. Holly Blue (RD only) 6. Green Hairstreak (RD only)     7. Red Admiral 8. Orange Tip 9. Small Copper

10. Common Blue 11. Dingy Skipper (BW only)     12. Large Skipper 13. Small Skipper 14. Essex Skipper 15. Meadow Brown 16. Ringlet 17. Marbled White 18. Speckled Wood

19. Gatekeeper 20. Green-veined White 21. Small White 22. Large White 23. Painted Lady (BW only) 24. Silver-washed Fritillary (BW only) 25. Small Heath 26. Brown Argus (*)

Still time for a Purple Hairstreak at Roughdown so I'm keeping my eyes peeled!

*NOTE 2 Sept 2014: Following the Brown Argus at Roughdown Common, I then found a colony of at least 13 individuals at Bovingdon Brickworks.