The Green Hairstreak was not recorded in my district of north Essex during the early 1990’s. It was long known just across the River Colne estuary, and at a handful of other sites in Essex such as the Danbury Ridge. I visited the Sandlings of Suffolk in those days to see Green Hairstreaks. They however started to appear in more sites in the county including some in the area. In 2005 there were several reports of new colonies.
A bypass was constructed for the villages of Weeley Heath and Little Clacton, in the early 1990’s and completed in 1995. A deep cutting was constructed through a watershed, and a high embankment was built in order to cross a railway and stream. Local naturalists were pleased that intrusions into good wildlife habitats were few and indeed new features linked some of the previously isolated ones.
The other welcome innovation was the establishment of vegetation on the banks. Wildflower seeds, along with seeds of Gorse and Broom were splattered on to the road-side banks, possibly in a slurry mix. Though some of the flowers were not of local provenance, and in some cases were not native to the area, the result was pleasing. Visitors to Clacton were very impressed with several miles of seasonal yellow blossom of Gorse and Broom.
In 2006, spurred on by good weather on the way home from work, I stopped in a lay-by in the deepest cutting and was delighted to discover several Green Hairstreaks, along with several other species. In 2007 on May 1st, in this same spot there were at least 20 individuals in the immediate vicinity of the lay by, and on both sides of the road.
In 2008 I discovered a similar density of Green Hairstreaks on May 9th, which prompted me to investigate the entire five kilometres of the road. I took the cycle stopping off in suitable looking spots and was surprised to see the butterflies along nearly the whole length, the only exception being the northernmost part which was being thrashed by a cool wind at the time.
In my text books, it was suggested that Gorse was likely to be the main food plant in areas such as Tendring, but several cases have been observed of Birdsfoot Trefoil, being the usual food plant.
The key to the success on the bypass has been the way that vegetation was established. Already after about ten years there has been a dieing off of Broom, though this has in places germinated again. However there are signs of habitat succession with establishment of tree saplings in places. It is hoped that resources may be found to maintain this useful wildlife corridor in the future.