John Tyler talks to us about The Glow-worm.
You studied Zoology at Oxford and have spent over 40 years in nature conservation. When did glow-worms become your particular fascination?
I have always loved insects and I was shown my first glow-worm when I was in my teens, by a friend who was lucky enough to have them in his garden. I couldn’t believe that such a bright light could come from a living creature, and I was hooked! When I was looking for a subject for my Masters dissertation glow-worms were the obvious choice, and it has all rolled on from there.
The book covers feeding, growth, self-defence and breeding across the glow-worm's life. Is there one stage of the life cycle that surprised you most when you first studied it closely?
I would guess that at least 90% of all the studies that have ever been done on glow-worms have focussed on the adult female and her amazing light display, whereas for many years we knew remarkably little about the larva, even though it makes up some 95% of the glow-worm’s life. I think my own most exciting ‘eureka moment’ was when I discovered how it defends itself against ants. I just put a larva on a huge wood ant nest, swarming with ferocious workers, and watched what happened. To my amazement the larva produced a row of white ‘buds’ along either side of its body, which somehow instantly repelled any ant that touched them. Similar structures had been observed in other fireflies but this was the first time that it had been seen in our glow-worm and in an age when so much research involves banks of highly technical scientific research equipment this is such a nice example of the sorts of discoveries which can still be made by anyone, using nothing more than a glow-worm larva, an ant nest and a sense of curiosity.
Glow-worm eggs glowing shortly before hatching
The book includes microscopic-level photography of the Glow-worm. What can we see at that scale that changes how you think about this insect?
Wanting to know more about the defensive ‘buds’ on the glow-worm larva, my friend Ernest Trice and I spent many happy hours studying them at the microscopic level and discovered that each one, just a fraction of a millimetre across, consists of hundreds of ‘balloons’ which we think burst when touched by an ant, releasing a poison to repel them. To me one of the wonderful things about glow-worms, or any other organism, is that by looking more closely ever more layers of detail and evolutionary design are revealed. There is always something new to discover.
The larva's skin viewed with a scanning electron microscope © University of Sussex
The Glow-worm is aimed at everyone from professional researchers to someone who's simply noticed a green glow on an evening walk. How did you balance scientific accuracy with keeping jargon to a minimum?
Over many years entomologists have developed their own language, with a technical name for virtually every part of an insect’s body, which can be very off-putting for a general reader, so I have tried to use terms which can be easily understood by anyone. At the same time I have included references to the scientific papers on which my statements are based, so that the reader can explore each one in more depth. I know that I’m biased, but even for someone with no real interest in insects there is something particularly fascinating and enchanting about glow-worms and I wanted to make this book as accessible as possible (in fact it’s the book that I wish I had had as that teenager seeing my first glow-worm!).
Across your decades spent studying this enigmatic species, is there one moment or encounter that stands out as favourite or most memorable?
On a good night, from one spot you may be lucky enough to see four or five displaying glow-worms at the same time, but my most vivid memory is of coming across a dense patch made up of of dozens of females all glowing brightly. It was like looking down on a small village in the dark. Sadly that was nearly fifty years ago now and it is very rare to see that sort of density today.
A glow-worm larva playing dead and glowing
For a reader who finishes this book and wants to find glow-worms themselves, what practical advice would you give them?
With so few of us out wandering in the countryside after dark, many people have never seen a glow-worm and yet most of us live within a few miles of a population, so I devote the last chapter of the book to suggesting how the reader can enjoy the sight of glow-worms for themselves. Many local conservation organisations can point you to a nearby glow-worm site and some even run guided night-time walks to see them. Glow-worms favour habitats which combine reasonably dense vegetation with more open areas, especially those which have existed for many years and are not too exposed to artificial lighting, so good places to search include unlit country lanes, old village greens and commons, rough grassland and scrub, and the rides, clearings and margins of ancient woodland. The best time to search for them is generally from mid-June to mid-July, preferably on a moonless or overcast evening, from about an hour after sunset. It may take time to find them but it will be well worth the effort!
Female glow-worms displaying within sight of the M40 in Oxfordshire © Robin Scagell
You describe the glow-worm as being "in decline and under threat." What is driving that decline and what can ordinary landowners, gardeners or local conservation groups practically do to help populations recover?
As yet we know very little about what is causing the apparent decline in glow-worm numbers, but it is likely to be a combination of factors such as the loss, deterioration and fragmentation of their habitat; chemical and light pollution; and climate change. All of these are also causing many other animal and plant species to struggle, so any steps that we take to improve the glow-worm’s prospects are likely to benefit other wildlife too.
There are plenty of things that we can all do to improve the situation, whether as individuals or as organisations. These include searching for previously unrecorded glow-worm populations (more are found every year, thanks to a growing number of volunteer recorders); reducing our use of pesticides; protecting and maintaining existing glow-worm habitats and creating new ones; and eliminating unnecessary artificial lighting. With so much house-building taking place across the UK at the moment we also need to make sure that politicians, planners and developers take into account the needs of glow-worms and other wildlife when considering new projects.
Order your copy of The Glow-worm here.
