Sunday, 3 August 2014

A Visit to the Brick Ponds at Hertford Heath

18th July 2014

I did eventually manage to find some of the rather scarce Emerald Damselflies at the Amwell Dragonfly Trail, but today I thought I would go to a rather more reliable site. Not only are you far more likely to find Emerald Damselflies here but they are also much more likely to be closer for photography. And the site that I am referring to?.....the "Brick Ponds" at Hertford Heath Nature Reserve.

The “Brick Ponds” are the result of excavating clay from what was then open grazed heathland. These ponds tend to dry up in dry seasons, but when they hold water are rich in dragonfly fauna. The clay was used to make bricks on site, to construct the small row of cottages in Roundings Road, next to the College Arms. The cottages, built in ca.1805, were for the staff of the new East India College, which subsequently became Haileybury College, the owners of the site.

I parked alongside the College Arms and walked down the road just 50 yards and entered the reserve. After walking about 100 yards through woodland you emerge on the heath with the Brick Ponds on your right. The heath itself was fairly active with several insects on view including Soldier Beetles and this superb Great Pied Hoverfly.

The grassland was also a cacophony of sound, a mixture of grasshoppers and the continuous high-pitched buzz of the Roesel's Bush-cricket. Until the early 20th century, Roesel’s Bush-cricket was only found on the south-east coast, but recent years have seen a rapid expansion in its range, particularly helped by roadside rough grassland and scrub providing a 'corridor' for it to travel along. It is particularly conspicuous by the creamy edge to the thorax.

Following the heavy winter rains the Brick Ponds were just one big lake, but now they have reverted to their traditional seasonal pond status and are nearly dry. Luckily, however, they were still wet enough to hold a few dragonflies with the muddy margins allowing access to photograph them. Most of the blue damsels were Azures, and this Common Blue was the exception as they normally prefer larger bodies of open water.

Ruddy Darters were everywhere and seem to like the slightly acidic pools. In fact, around the pools, it is normally very hard to find a Common Darter.

But the main purpose of my visit today was to find and photograph Emerald Damselflies, and I was not to be disappointed. Emeralds are not numerous at Hertford Heath but can normally be found in small numbers at the Brick Ponds and the nearby Sphagnum Pool. Today the Sphagnum Pool was virtually dry but the Brick Ponds still had enough water to attract up to six Emeralds. Success at last and what a superb insect they are.

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