The Brown Hairstreak Returns To Northamptonshire!

The 20th of December 2023 was a momentous day for butterfly recording in Northamptonshire. It was on this day that Brian Laney, while checking Blackthorns along a quiet footpath in the south of the county, found a butterfly egg. However, this egg was a very special one as it was the egg of a Brown Hairstreak! What makes this record amazing is the fact that the Brown Hairstreak vanished from the county in the mid-C20th, and since then they have been considered extinct. So, this is the first record for over half a century and now Northamptonshire can claim the Brown Hairstreak back as a breeding species.

This photo is of the actual egg found by Brian, and many thanks to him for allowing me to use it on this website.

Now of course you may be forgiven for wondering what Brian was doing down a lonely footpath looking for the eggs of a butterfly that has long been considered extinct in the county.

Well the truth is we have known for some time that they were going to arrive, it was just a matter of exactly when it would happen.

Over the years prior to this, it became apparent that the Brown Hairstreak was quite rapidly increasing its range in the neighbouring counties of Oxfordshire and Warwickshire

. I was sent a distribution map of the eggs that had been found and you could clearly see that they were getting tantalisingly close to the Northamptonshire border. Brian and I then joined forces and together over the winters from early 2018, we have scoured the footpaths and hedgerows looking for the tiny white eggs of the Brown Hairstreak on the young blackthorns.

As the most likely places for the Brown Hairstreak to colonise were in the south of the county, particularly around Croughton, we concentrated our efforts around there. Over the years we have searched as many hedgerows as we could and as well as Croughton we have covered footpaths around Aynho, Charlton, Brackley, Evenley, Hinton-in-the Hedges and King’s Sutton. This may to some people sound quite laborious, but it certainly wasn’t the case. Brian’s infectious enthusiasm and incredible botanical knowledge meant everyday searching was always great fun and we certainly had a lot of laughs when we were in the field! As we were often rather close to a military airbase the ever-present possibility of having our “collars felt” by the authorities also added to our adventures!

Brian and I searching for Brown Hairstreak eggs

On Christmas Eve, a few days after his amazing find, Brian and I decided to head down to the site to explore further and I am very pleased to say that we had a rather successful visit. We parked in the large lay-by on the A43 so we could have a walk along the footpath that runs along the border with Oxfordshire. We hadn’t gone too far along the path before Brian managed to find another Brown Hairstreak egg and here is a photo of it………

Then a bit further along the footpath Brian found yet another! Here is the photo of that one……….

We checked as many of the blackthorns as we could along this path but we couldn’t find any more along here. Eventually, we reached the path Brian had explored on the 20th and we had a slow wander up, checking as many blackthorns as possible before Brian showed me the egg he had previously found. Here is a photo of that one (it is the same egg that Brian photographed with his mobile phone)………..

We continued to walk towards the airbase and then I found an egg on a small blackthorn to the left of the path, here is a photo of that one……….

Finally, Brian found the last one of the walk further north on the same path, here is the photo of that one too………

So, after today’s walk, this now brings the total number of Brown Hairstreak eggs found to five. If you are planning on visiting to look for eggs, or if you are now planning on visiting next year to look for the adults (I know I will be) the location is along the footpath that runs south of RAF Croughton and east/west along the county boundary with Oxfordshire. There is a large lay-by on the A43 which is a good place to park to gain access to the paths. There is no doubt that there will be more eggs in the surrounding area so if anyone visiting does find any please let me know so we can record them. Please also be mindful of the fact that RAF Croughton is a working military base so abide by any rules and be careful which direction you are pointing the camera. Here is a map showing the location of the eggs recorded today, the area marked with pale shading is Oxfordshire.

After all the many miles we have walked over the years I am really pleased that Brian was the person who found the first egg securing the Brown Hairstreak’s place back on the list of Northamptonshire’s butterfly species. If you are wondering what an adult Brown Hairstreak looks like here is a photo I took of one many years ago at RSPB Otmoor.