Enchanted and Enthralled, Bewitched and Beguiled. My summer as a male glow-worm!

Iain Webb, Cambridge City Greenways Project Officer, charts his glow-worm spotting adventures during the summer months

Have you seen a glow-worm in the UK? If you haven’t, then chances are they are closer than you think. Glow-worms are iconic. These magical creatures, illuminating sheltered, wild places have garnered much interest from poets, writers and country folk. The great nature-enthused poet William Wordsworth called them “Earth born stars”. Very apt when you see them twinkling in vegetation on a dark summer night. Glow-worms are mentioned in Shakespeare’s Hamlet, by Samuel Taylor Coleridge and there was the very discreet but very valuable individual in James and the Giant Peach by Roald Dahl. 

I had dabbled in a bit of glow-worm watching previously, the Chalk and Cheese events at Cherry Hinton Chalk Pits being the major one, but never managed to do much more. My summer nights are usually filled with showing people the delights of the bat world, so there wasn’t much room for glow-worms as well. However, that all changed this year as the 2020 bat punt safari season was cancelled and suddenly my evenings were free! 

It all started with wanting to see turtle doves. The Trust has been working with the Wellcome Trust’s Genome Campus in South Cambridgeshire for many years, advising the management of their nature reserve. A purring male turtle dove had appeared there in early May and I wanted to see this rapidly declining species at least once this year.

The trials and tribulations of a Covid-controlled household meant that I didn’t arrive at the site until quite late in the evening, far too late for turtle dove to be purring. But, as I have discovered over the years, when you have managed to get out it is always worth staying out. It is far better than going back home, in my opinion! It is safe to say that you will see something amazing, even if it wasn’t what you planned to see. More about that later.

I knew there were glow-worms present at that reserve as I had seen a couple over the previous few years. So, having missed out on my primary quarry, I waited until it got suitably dark and then ventured out. It didn’t take long until I saw one of my top wildlife spectacles of the natural world - a glow-worm. Her brilliant glow had attracted 2 males. I continued wandering around and saw an impressive total of 5 glowing females, the most I had seen on the site.

After that first reconnection with Lady Lampyris, (Lampyris is the genus name for glow-worms) I decided that it was to be a glow-worm summer for me. I already knew of a couple of sites but I wanted to find more. To help with this I visited a wonderful website, www.glowworms.co.uk. Glow-worm enthusiasts are encouraged to submit their records, so you can see whereabouts glow-worms have been seen. So with these recent records for Cambridgeshire I set to work, poring over maps, checking grid references preparing myself to dive into the nocturnal world of the glow-worm. 

I thought that glow-worms were scarce in Cambridgeshire, relicts of a time when herb rich grass verges and meadows were strewn more liberally throughout the landscape. But as you will find out, I was pleasantly surprised! The larvae are relatively mobile for something so small, covering a couple of hundred metres a year. As voracious mollusc eaters, they spend 1 or 2 summers feeding up and then settle down in a pupae. When they pupate into an adult they don’t feed so have only 2 to 3 weeks to mate. Once a female glow-worm has mated, she turns out her light, lays her eggs and dies. Pretty drastic, but not uncommon in the natural world.
As the season progressed I talked to all those that would listen about my nocturnal discoveries. Very few people have actually seen a glow-worm in this country. If someone had seen them they were most likely in the US or New Zealand or mainland Europe. On the way I enthused anyone who I saw, even encouraging someone to carry on with weekly monitoring.

During my immersion into glow-worm life, I felt I was doing just what male glow-worms do. Eyes down, head turning methodically left and right, looking for a tell-tale pale green spark. Then honing in on the smallest flash. Many times, they would be false alarms. White campion flowers, broken glass, discarded plastic wrappers; in the rapidly descending light they catch the eye and trick the brain. After a no doubt comical-looking sway back and forth, eyes fixed (checking to see if you can get a better view from a different angle) a resigned acceptance that it isn’t one and the search continues. Something more commonplace nowadays, and something that the males haven’t evolved to deal with, is artificial light. Alongside habitat destruction/fragmentation the increase in artificial light is one of the major factors causing a decline in glow-worm populations. The bright glare distracts them from the gentle perfect green light of the female.

I visited sites from the blog that hadn’t had a record for a few years, up to 11 years at one. They were still there. Beautiful bright beacons shining and winking. On several occasions sites that previously had records of up to 5 glowing females, with a bit of diligent searching, turned up many more. One site that had previously recorded a maximum of 4, I made a count of 38 and subsequent to that I heard from a friend that they also visited a different part of the site and had counted another 11. This site is extensive, so who knows the true size of this population.

One evening started by a very non-descript road verge that had recorded two glowing females a couple of years ago. After being pleasantly surprised in seeing my first one, the site didn’t look that great. My heart starting to race, my breathe short and rapid, thrilled by the continual appearance of another, then another, then yet another glow-worm until finishing in a near hypnotic trance after relishing the experience of a final total of 55!  I can now see why they have been such a large part of folklore and fairy-tale.

The sites I searched in were not just nature reserves. I searched sites where remnants of a bygone era (scheduled monuments, ancient byways, churchyards, disused railways) still mark the landscape. Those old sites that still contain habitat haven’t changed markedly over the past hundred years. So when 97% of meadows have disappeared these sites hold the only remaining habitat suitable for glow-worms. A few sites had been recently created, less than 20 years old, and glow-worms ‘moved in’ from adjacent habitat. Railways and road cuttings/verges were much the common feature for these sites. Glow-worms, like many, many other species are finding it more and more difficult to find space to survive, let alone thrive, in the world we are now creating.

There is a potential hit and miss with visiting sites. At that first site many of the females were well attended by males, so their lights would no longer shine. So visiting a known site and not seeing any, doesn’t mean they are not there. The population maybe quite small and the females are mated quickly so don’t shine for very long and are then missed. However, not all the adults pupate at the same time, so there may be glowing individuals coming and going over quite a few weeks. A great excuse to go back to sites again!

Just spending more time out in suitable habitat in not necessarily suitable weather can bring about amazing discoveries. One night, hoping that the long predicted rain would actually stop at dusk, as one website suggested, it continued unabated for several hours. I was out in a parish that had a couple of known populations. I arrived at about 9.30, any glowing wouldn’t start for another 45 minutes at least, with the weather looking decidedly unsuitable I thought I would  go for a walk around the site to get to know it before coming back another evening with better weather. I walked around a very pleasant parish managed site, rough grassland, old orchard, scrub and riparian woodland and marsh. The rain was falling a bit harder, and I had foolishly forgotten my hat. But, it was warm, and more importantly I was out. So, I headed off to look for another site nearby that glow-worms had been recorded at. It was a byway, management being of the light-touch variety. So there were thick hedges on either side and thin ribbons of grass beneath. Not expecting to see anything, primarily because it was raining, I trudged along. But, much too my amazement, after 5 or so minutes, I saw something! An obvious green spot in the undergrowth. And there she was, a glow-worm glowing! (In the film below you can hear the rain)

Glow worm video by Iain Webb

When you see one glow-worm there is always the chance of seeing more! So, I continued, head turning from left to right not quite believing I had seen one when, there! Another one! And another and another! Eventually I got to a grand total (I thought) of 6. 

I hadn’t seen one for a good 100 metres, but rather than turn round I decided to continue, in for a penny and all that. Up over a rise the byway widened out, the hedges were now typical South Cambridgeshire farmland size and there was a broad grass verge either side. Perfect! But where were the glow-worms? I was getting a bit despondent, I could see the A10 up ahead, which marked the end of the site. But, not 50 metres from the end there was another bright green fleck! Then another and another (you get the idea). The total finally reached a very respectable 12! Being very pleased with myself, this was a new population, I wandered down to the A10 just to see where I was. It was now 10.45pm, I was thoroughly soaked and I was thinking about a round of warm cheese on toast and then bed. But, the night had other plans. Looking across the carriageway, is that a light by the footpath? No, it’s just one of those solar lights they sink into the edges of bike paths, isn’t it? Crossing the road I realised how wrong I was. It was a glow-worm doing what she does best! I was dumbstruck. It wasn’t just one! Dotted along the very innocuous looking footpath, right by the A10, and across the adjacent ditch there was a total of, I kid you not, 22 female glow-worms! 

Glow worm video by road - Iain Webb

If there is a healthy population of glow-worms here in this VERY non-descript piece of grassland and scrub where else could they be?! As you could imagine I was buzzing (actually it should be glowing) with excitement. I decided to walk back to the original site to see if any females were glowing there. It was very much still raining but, after already seeing glow-worms not worrying about the heavy precipitation I was wanting to keep looking! After a couple of minutes, sense started to seep into my brain and I realised that to walk around the whole site at male glow-worm pace would take a good 20 minutes. It was late and was only going to get later. I had already seen a very impressive number of glow-worms, and discovered two new populations! So, I decided to head back to the van and head home. But, in the small car-park, nestled in the dark side of some bushes (there was a fair amount of light pollution from the adjacent residential area) were two female glow-worms!!! 
Buoyed by this additional sighting I nigh-on skipped back to the van. I headed home but, not content with all that I had seen that night, I took an ever-so slight detour off my homeward journey and stopped off at the Trust’s Shepreth Moor nature reserve. I had seen one female three weeks previously and wondered ‘surely a rich site such as this would hold more than that!’ Focussing on the part of the site where I found one before 5 females revealed their presence with that tell-tale glow. 

Finally, getting home I reflected on the monumental night of glow-worm hunting and watching I had just had. I had seen 47 female glow-worms in five populations at five sites, two of them new! I had my cheese on toast went to bed and left the world of glow-worms with a smile on my face (and a very damp patch on the driver’s seat of the van).

Over the six or so weeks I visited a total of 21 sites (including 5 Trust reserves), found 8 new populations and saw a total of 222 glowing females! Glow-worms seem to have a discreet distribution in the county, with pockets (or constellations, if you will) of occupied sites. But that is not to say that they aren’t found between these pockets, it is just that not so many people are looking for them. Why am I making a fuss of glow-worms? They are not on any special ‘list’, warranting special assistance to survive. In my brief experience and looking at www.glowworms.co.uk it seems they are relatively common. But it’s presence overshadows what has been lost. It is one of the saddest things about working in conservation for the past 25 years, the constant slow loss of nature. Whether it be certain species still found everywhere, but populations are getting thinner, such as skylark. Or species that are disappearing from former haunts at a shocking rate, such as turtle dove, water vole, cornflower etc. They added essential diversity to habitats and the landscape. Once an everyday part of a walk in the English countryside, now consigned to just dots on a map showing where it used to be found. It is these many species that suffer the constant diminishing of the wild. The losing of rough field corners, the slicing up of open land into smaller and smaller pieces, the banishing of night’s mystery by the constant glow of artificial light. 

Glow-worms don’t need a special or scarce habitat, they are not reliant on a particular plant, all they need is a ready supply of snails, extensive grassland and a night sky lit only with the stars and the moon. They are being left behind by the modern modification of the countryside. One of those species that were once all too common has now become all too scarce. And no amount of new colonists or re-established species can conceal the truth that a species with very simple needs cannot be accommodated in the world we are creating. The hedgehog is another obvious one, swifts, starlings and countless other less obvious species are being consigned to being scarce rather than common in the wider landscape. The diminishment in the diversity of nature is the diminishment of the human experience.

Saying that, I am convinced that there are new populations of glow-worms waiting to be discovered in the county and old ones to be rediscovered. The more people out there rambling (safely) along footpath, byway and verge in the dead of night, the more chance that isolated populations will be found, appreciated, their habitat managed appropriately and their populations expanded. 

So why don’t you make 2021 your summer for stepping out as the sun dips down. Let your eyes adjust to the darkness and discover your local glow-worms. 

I feel a certain amount of comfort knowing that every summer evening, at a good number of sites in South Cambridgeshire, as the sun slides down below the horizon there are female glow-worms, slowly working their way up grass stems, to ready themselves to start the hypnotic light show that is the top-class act in the UK’s wildlife spectacle. But one so modest and retiring, doing her own thing, to keep the species going, with no fanfare, no loud or beautiful song, just the slow steady swaying of that brilliant bright green light. 

A true star!