July is the month when I become another year older. Fortunately for me, my birthday coincides with the peak flight-time for one of our most beautiful butterflies, the Chalkhill Blue. 

Of the handful of places where it can be seen in our counties, my favourite of all is Hexton Chalk Pit Nature Reserve in the far north of Hertfordshire.  As its name suggests, this is a place where chalk was quarried. The former industrial use has created an undulating landform, full of mounds and hollows, ups and downs – one of our best reserves for a satisfying game of hide and seek if you have children in your charge. 

The diverse topography also creates a wonderful range of niches and microclimates where chalkland plants such as Milkwort and Sainfoin thrive. The habitat here is carefully cared for by the Trust’s reserves team, with the aid of sheep and more recently goats, whose hungry munching prevents vigorous grasses from swamping smaller plants. Another plant which thrives here is Horseshoe Vetch, which happens to be the foodplant for caterpillars of the Chalkhill Blue. 

The first adults are on the wing from the end of the first week of July but the peak is usually during the third week. If you are going to visit, have a look at the weather forecast and aim for a warm sunny day around the 20th. Numbers always vary from year to year and are affected particularly by climatic conditions. Following the washout summer in 2012, which you may remember was the year of the London Olympics, the populations of Chalkhill Blues exploded and at Hexton in 2013 there were many thousands seen on a few days – quite literally clouds of butterflies! For those lucky enough to witness the event, it will no doubt be remembered as one of the greatest wildlife spectacles in Hertfordshire.

Whilst at Hexton Chalk Pit Nature Reserve…

See this: Watch the shivers and shakes of the seed heads of Quaking Grass as it tremors in the warm summer breeze.

Smell this: Enjoy the aromatic scent of Wild Thyme which forms low-growing mats across the pits.

Hear this: Listen out for the jolly whistling of Red Kites as they drift across the undulating landscape.

Feel this: Crumble a small piece of chalk in your fingers remembering that it’s formed from the remains of tiny organisms that lived and died in clear warm seas that covered this area 70-100 million years ago.