Sunday 24 August 2014

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.


Martin Parr said...

Excellent work Lucy, a great find with the Brown Argus, I haven't seen many locally. The only Triolus luridus that I've seen locally was at Maple lodge a couple of years back - and the only other ones I've seen were at Whitecross Green wood - so thats a great find! Excellent fieldwork and great pics!

Will listen out for news on the planned fracking in the area with renewed interest after your dream! ;0)

Cheers, Martin

Lucy @ A Natural Interlude said...

lol, thank you, Martin :-).

I hadn't heard of Whitecross Green Wood but have since looked it up. Not too far from Finemere Woods which is where I first saw a Silver-washed Fritillary. An area to visit next summer perhaps. I've still never seen a Purple Emperor butterfly which both sites seem to attract.

Martin Parr said...

You are better off at Finemere for them, but Whitecross has black and brown hairstreaks and white admiral - and used to have Wood white. I got a shot of what I think was the last recorded one there. The warden told me they hadn't been seen since the year before my shot, so I was able to disprove that!
Also not far from ashton rowant for silver spotted skipper...!

Cheers, Martin

Lucy @ A Natural Interlude said...

Wood White, Black and Brown Hairstreaks…all new to me. The list of places to visit next year is growing rapidly, lol. Thanks Martin :-)