Thursday, 23 July 2009

Thursday 23rd.July 2009

Just one question was on my mind , as I set off for High Elms , are the White Letter Hairstreaks out yet ? On arrival , I first checked the site on the edge of the Conservation Field , where I had sightings last year . In perfect conditions , sheltered from a brisk wind , there were several species nectaring on the Bramble and Marjoram , but no sign of the WLHs . I had three Silver Washed Fritillary males and a Painted Lady , fly purposefully along the edge of the woodland , and soon afterwards , my attention was drawn to ground level , with some unusual coloured wings . As I got closer , I realized that it was not a rare species , but a common Meadow Brown .
This form of colour or pattern change is called 'aberration' , and can be found in several species . Another example is the blue spots on the hindwing of some Small Coppers . With nothing found , I headed towards the Small Glade and the Orchid Bank , both sites having Wych Elms , and colonies have been found on both trees in past years . On the way , I passed several small Wych Elms along the rides , and on one of them , I disturbed a moth as I passed , which flew on and settled on a Beech . For once , I don't have to ask for ID , as I record this Elm specialist each year on the site , it is the Clouded Magpie . When I first spotted it some years ago , I thought it was something really special , well it is really , but if Elms or Wych Elms are on a site , there is a good chance that this moth is too , as it's larvae feed solely on them . At the Small Glade , I was met by a very pristine male Brimstone , that was so eagerly nectaring on Marjoram that it's head finished up blurry due to his movement . In the same glade , whilst searching for WLHs , I came across yet another pair of mating Gatekeepers , not surprising that this species is doing so well . At the front of this glade , are the trees where the SWFs were constantly egg laying , up to five at a time , but this year they don't seem to be as happy using them . They seem much happier with the trees between this glade and the Orchid Bank , just to the side of the main wide ride . That was where I found this female , looking a bit worn now , taking a rest from her exertions . When she was ready , she flew across to a Scots Pine , and deposited 5 eggs on the shady side of the tree . She then fluttered down to rest again , before repeating the operation . This is what it is all about , one of the five eggs that she layed , whilst I watched . A small white egg , this one layed on the leaf of Ivy growing on the trunk , looking like a Sea Urchin or a minature jelly , turned out of a mould . When the caterpillar hatches , it will climb down the trunk , and it's foodplant , Violets , will be found all around . The reason for not using the trees last year , could be that the females do not consider that there is enough foodplant around them for their offspring , not surprising given the number of caterpillars that fed on the Violets last Autumn and again this Spring , before pupating and becoming the beautiful specimens seen flying around now . I checked out the Orchid Bank , but still no sign of WLHs . The flowers on the stands of Hemp Agrimony are well open now , I just hope that we haven't lost the colony following two bad Summers and a hard Winter . There is still time , so it's fingers crossed . Coming home for lunch , it started to rain and I thought that was it for the day , but it passed through , so I spent an hour on the Common this afternoon , in breezy and at times , damp conditions . Almost the first butterfly I found was a pristine Brown Argus , and when it eventually opened it's wings , it turned out to be a female , my first this year , identified as such by no 'blueing' of the abdomen , and the orange spots on the forewing , not fading towards the top , as they do on the male . From the look of her , she had only just emerged . The main object of the visit , was to check on the Small Tortioseshell eggs , layed on a stand of Nettles , in a very windy position . Fortunately , I tied some grass around the stem , so was able to find them . Turning over the leaf , I could see that most of the eggs had gone , and some of the leaf had been eaten . Unsure exactly what had happened , I looked around , and noticed the leaf above the one the eggs were layed on , was rolled over , and a silk tent constructed over the two edges . With a magnifying glass , I could make out very small black caterpillars , moving about within the silk tent . Hopefully , these are the offspring . Strangely , whilst I am looking at the caterpillars , a Comma flies into the middle of the Nettles . I watch it , and see the abdomen touching down on the leaves in the middle of the stand . She flies off a couple of times , but comes back and carries on laying . I tried to get a shot , but with the wind and where she was laying , I failed . I had a look around the rest of the site , but before heading home , returned to the Nettles , to find a Red Admiral laying eggs on the stand . Both Commas and Red Admirals lay single eggs on the upper side of Nettle leaves , whereas the Small Tortoiseshell and the Peacock lay their's in batches on the underside of the Nettle leaves . Now , I can hopefully look forward to finding the chrysalis of all three species on that stand of Nettles , if everything goes to plan .All over the grassland on the Common , are hundreds of Field Grasshoppers , ranging from juveniles , to fully fledged adults .


Warren Baker said...

A fact pack post again Greenie! Far to many for me to take in on one reading. So tell me, what is the difference in the hindwing of CB and BA ?

Greenie said...

Warren ,
Firstly , to avoid confusion .
The wings of a butterfly are , forewings-the ones either side of the head and the hindwings-the two behind them along the abdomen .
Topwing is looking down , like on a Peacock showing it's eyes etc , and underwing is the dark underside , almost black on the Peacock .
Your question re. Common Blue/Brown Argus is answered in your own photos .
If you look at the right hand of pair of CBs , on the underwing , in line with and above the head , is a 'boomerang' shaped mark with a spot beneath it .
If you now look at the BA shot on the yellow/white flower , the 'boomerang' is there , bot not the spot beneath .
Be careful though ,the wings need to be slightly apart to see whether the spot is there or not . I have a good comparison/side by side shot , I'll try and remember to put it on my next post .

Warren Baker said...

Thamks for that greenie,
I'll have it imprinted on my brain now!