Local community site for Broadstone, Dorset, since 1999

Nature Diary – July 2015


Looking for the Large Blue


large blue butterfly

Collard Hill in Somerset is the only place in the UK where the public have access to see this very rare butterfly; the reserve is run by the National Trust and was officially opened in 2002. I just had to go there and hope to see, or at least get a glimpse, of this Aurelian treasure and maybe be lucky enough to get a photograph of this wonderful blue butterfly. I heard that the fast flying migratory long tailed blue (Lampides boeticus) had been seen here recently and the scarce Brown Hairstreak (Thecla betulae) can be found here in Aug/Sept on Blackthorn scrub. So if you are into butterflies make a note in your diary, this is a rather special site and definitely needs to be paid a visit. Having arrived on site early before all the butterfly paparazzi, I mention this because this site is visited by hundreds of Lepidopterists every year hoping to see a freshly emerged (Maculinea arion). Collard Hill has become a Mecca for many people, like the bluebells at Kingston Lacy it has to be visited every year. This butterfly became extinct in this country in 1979 from the last known colony in Devon, but was reintroduced, I believe, in 1985 with a Baltic race of Large Blue. This wonderful butterfly needs two things to survive, wild thyme (Thymus serpyllum) to lay its eggs, on which the caterpillar feed exclusively during its first few weeks of life until after its third moult the caterpillar will then drop to the ground and wait to be picked up by a passing red ant, but not any red ant, it has to be (Myrmica sabuleti). The caterpillar now in its fourth instar is taken into the ants nest being attracted by the sweet secretions of the larvae where they proceed to milk it, and in turn the caterpillar becomes carnivorous feeding on young ant larvae. It is here the caterpillar hibernates until spring, when it pupates and emerges from the nest a perfect adult butterfly; any other Myrmica species would have eaten the caterpillar seeing it as an imposter. We started our search at the top of this very steep hill gradually making our way down passing one other person looking for (Arion) when asked, he said he had only seen one that morning but it was still early. We carried on meandering downhill slowly and carefully, one slip and you were back in Dorset, well not quite, you could see the county from this hill that’s how high we were. Other butterflies were starting to appear now it was getting warmer, Meadow Browns (Maniola jurtina), Marbled Whites (Melanargia galathea) and Common Blues (Polyommatus icarus). Also there was a plant of which there were several I had not seen before, the waxy leaved Yellow Wort (Blackstonia perfoliata) but no Large Blue. We decided to split up to cover more ground, as I said earlier this is not the easiest of places to walk. My companion was the first to spot one, I hurried to where he was pointing as best I could without slipping but it decided to move and quickly disappeared before I could get anywhere near close enough for a photograph. We carried on searching, it was now starting to get hot and groups of people were starting to appear but it wasn’t long before we found another that was more obliging. We quickly photographed it, it’s not the best of photos as you can see, but you can’t ask a butterfly to open its wings while you take a photo, you just have to snap away before it decides to move, this one decided to move on. It was now I realised just how popular the Large Blue has become as we were suddenly surrounded by people with cameras and lenses of all makes and sizes, where had they all come from? We decided it was now time for us to make a move and head back to the car, myself feeling very lucky having seen this extremely rare butterfly whose life history and extraordinary symbiosis with ants was once not known.


female grass snake

As it was still quite early maybe we could look in on the way home at SHAPWICK HEATH which was not far away. This reserve with extensive amounts of water and reed beds is managed by English Nature and is part of the Somerset Levels/Avalon Marshes. I had never been here before and did not know what to expect. We left the small car park and slowly made our way along a track which was once the Glastonbury to Highbridge Railway, following a drain rich in Emperor and Chaser Dragonflies and Banded Demoiselles (Calopteryx splendens). To the left of this trail way was a large area of phragmities reeds alive with noisy Reed warblers and an occasional Cettis warbler making his presents known, and to the right an extensive wetland where in the distance I spotted a Great White Egret (Egretta alba) stalking the water margin for fish. This rare vagrant to Britain will soon be as common as its cousin the Little Egret (Egretta garzetta), before the 1980s this bird was a rare visitor now it seems to be everywhere. While I was watching this magnificent bird through my binoculars a beautiful Marsh Harrier appeared flying back and forth above the reeds then suddenly dropped down and disappeared. Above the water a pair of Hobbies were hunting for Dragonflies and other insects, to see these raptors here together was pure magic. After walking about half a mile we came to a small bridge which crossed over the drain then following a path through a copse we arrived at a hide which overlooked Ham Wall Nature Reserve where Bitterns and the Marsh Harriers nest, Barn owls can be seen here flying at dusk. I was told by a regular birder that Otters are regularly seen wandering over the marshes or hunting the drain, probably for moorhens, their favourite prey. A large flock of Lapwings, I should say a Deceit of Lapwings if I use the collective noun meaning a group came flying over and settled on a nearby field. These birds are not as common as they were in the 1950s although protected by the RSPB they were once protected by an Act of Parliament (the protection of Lapwings Act, 1928); the lapwing or peewit as it is also known, destroys large numbers of the snail (Galba truncatula), this small transparent 12mm fresh water mollusc that often lives in mud is the host of the embryonic form of the liver fluke in sheep; (ref: Ministry of Agriculture and Fisheries Bulletin no.140). Not having any cover of trees the heat had become unbearable so we decided to make our way back to the car park where there was a small woodland, we rested here on a sheltered seat for a while in the shade before making our way back home. While resting I spotted a large pile of grass cuttings and on the top a large piece of corrugated steel, obviously put there for reptiles. I just had to have a look and beneath this piece of tin was the biggest grass snake I had ever seen, it was probably a female, it looked over 900mm in length, most specimens of this size are female.


About Author

I am a retired groundsman and have lived in Broadstone for forty years. I am a volunteer warden for ARC monitoring the amphibians and reptiles that live on the Heath at Dunyeats Hill which I have been doing since 2008. I am also oology curator at the Bournemouth Natural Science Museum cataloguing their egg collections.

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