The UK Glow worm Survey Home Page

Glow worm picture
Glow worm, Lampyris noctiluca. Photo copyright Robin Scagell

Seen these??


We have received many reports of hundreds of glow worms or fireflies in trees, like these. They are not glow worms but laser decorations projected from a nearby house. Glow worms don't live in trees. Please do not send us reports of them!
Photo: Lisa Bignell

Seen a glow worm?
Please tell us where and when you saw it by using our online form.

Want to see one?
Find out where glow worms have been seen in our blog! Or join one of the limited number of glow-worm walks taking place during the summer months in 2023


Were you looking for The Gloworms folk music band? Click here

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The UK Glow worm Survey The UK glow worm survey began in 1990. It is run by Robin Scagell, and has no official status, funding or affiliation, but exists solely to gather information about a fascinating insect that most people don’t even realise exists in Britain. Information comes mostly from members of the public who see glow worms and want to know more about them. Before the survey started, it was said that there were fewer than 100 sites where glow worms could be found in the UK. The survey has shown that there are in fact hundreds of sites throughout the UK where they can be seen, and more sites are reported every year. Please note that we never give out or list details of glow worm sites on private land, other than to bona fide researchers, so if you have glow worms in your garden please tell us without worrying that you will get hordes of unwanted visitors in the dead of night! You can report a site to us by filling in an online form. The survey is now run within the national iRecord database, so results are stored securely and nationally. We do not send out any junk mail or sell address lists! You can add pictures to your records using the report form.

The survey has been publicised in particular by the Weekend Telegraph (July 2006), National Trust magazine (Summer 2005), BBC Wildlife Magazine, on BBC Radio 4, and by BBC TV’s Country File and Springwatch.

About glow worms

Key glow worm facts:

  • Only adult females glow brightly, to attract the flying males
  • Adult glow worms can't feed, so they can live only for 14-21 days or so
  • Once a female glow worm has mated, she turns out her light, lays eggs and dies
  • Leave glow worms where they are – they know best where they like to be
  • Don’t take glow worms home – they need specialised habitat
  • As we travel in our cars from one brightly streetlit area to another, we are unlikely to notice the tiny lights of glow-worms, about as bright as an LED indicator on a TV. Yet they are still to be found, and they may be more common than you think. But despite surveys over the years, researchers are still in the dark over the factors affecting the decline of glow worms, and even if they are declining everywhere. What is needed is the widest possible survey of the remaining glow-worm habitats, which is where you can help.

    The glow worm, Lampyris noctiluca, is not at all worm-like but is a beetle up to 25 mm long. Only the wingless female glows strongly, to attract the flying males. Each individual female has an adult glowing life of no more than a few weeks until she mates, since she dies soon after laying her eggs.

    After a few weeks the eggs hatch into larvae, and they remain as larvae for one or two further summers, feeding on small snails which they apparently paralyse before sucking them empty. The two- or maybe even three-year gap between a mating and the subsequent appearance of an adult helps to explain why you may find plenty on a site one year, yet few or none at all the next. And, of course, sites where they seem to have died out can’t be written off on the basis of a single night’s search, or even several nights in one season.

    How to tell adults from larvae
    Larva

    The adult female and larva look very similar at first sight, so you might need to look closely.

    Larvae
    Larva

  • Have pale spots at the rear edge of each segment (see picture at right and above)
  • Their glows are not very bright, and usually only last for a few seconds at a time, coming from two small points on the rear underside of their tail segments
  • Often move around slowly in search of prey, using their tail segments to help themselves along a bit like a caterpillar.
  • Can sometimes be seen on paths in daylight, particularly in spring

    Adults
    Glowing spots

  • Glow brightly and continuously from large areas on the final two segments with smaller spots on the final segment (only females glow noticeably – see picture at right). Insect rarely seen by day
  • The adult female has a completely matt black back with just a thin paler line down its centre
  • Usually remain in one spot either on the ground or clinging to a stem, curled so as to turn the glow upwards. Often move their tail segments from side to side.
  • The adult male is smaller and has black wing covers. He rarely glows.
  • You can see these differences in pictures in the gallery.

    Don't be confused by:
    'Firefly' laser projection. Glow worms don't live in trees! Pic: Robin Scagell (and projector owner!)
    Ladybird larva.
    Pic: Robin Scagell
    Carrion beetle larva
    Pic: Michael Cullen
    Ground beetle larva feeding on slug
    Pic: Andy Wilkinson

    None of the above? If what you've found looks nothing like these try a Google search on beetle larvae images!

    Where and when to look

    You can read an updated list of the site reports received by going to http://ukglowworms.blogspot.com/

    Where should you look for glow worms? Though they are said to favour chalky or limestone areas, they have been reported from many areas of Great Britain. The peak glowing period is evenings in June and July. People are often surprised to discover glow worms in gardens, hedgerows or railway embankments where they had never been noticed before. Disused railway lines are prime sites, in fact. Glow worms can also be found on cliffs, woodland rides, heathland and even valleys in Wales or Scotland which meet none of the above criteria! There are few counties in the UK where they are not found somewhere, though they are believed to be absent from the Isle of Man and Ireland.

    Having said that, I have had a report from Greystones, south of Dublin, which needs more recent confirmation. In 2009 I received a report that glow worms can be seen in the Wicklow Mountains but a request for confirmation to the Wicklow National Park went unanswered. And in 2009 I also heard from Richard Fisk, who spotted what looked like glow worms at Killilane near Rosslare. We really need verification of these reports by means of a photograph of the actual insects, so anyone in the southeast of Ireland is requested to keep their eyes peeled and a camera at the ready.

    Glow worms are found in Jersey, but not in Guernsey or Alderney.

    Click here to see a UK distribution map published in 2007 by the Biological Records Centre, which is the official recording centre for all UK species. It also shows pre-1980 records. In recent years many more sightings have been recorded, and for a detailed map of sites reported to iRecord since 2011, see this up-to-date map produced in early 2024. There is also an old list of UK sites in the historical county-by-county lists. To access a detailed map and listing of recently recorded sites near to you, register with iRecord, and on the Explore menu filter results by Lampyris noctiluca.

    Some people like to keep glow-worm sites secret, for fear of the ‘egg-collector’ mentality, which I appreciate. But I believe that it’s better to educate people that glow worms are best left alone rather than taken in glass jars to entertain the kids, and the sites that are well-known and feature in glow-worm walks do not suffer any obvious problems. There are far greater threats to them from ignorance and from lack of knowledge that the glow worms are there.

    Wherever you find small snails, though unfortunately not the large common-or-garden variety, it’s worth looking for glow worms. They prefer open grass or hedges to woodland, but rarely are they to be found on land which has been ‘improved’ for agriculture. Look for them from late May to early September (with a peak in mid July), as soon as it gets dark. They glow for a few hours at a time, and usually stop glowing soon after mating. If you do see glow worms, don’t disturb them and certainly don’t take them home as trophies, no matter how many there are on a site. Their continued existence at your site could be on a knife-edge. But a short look by torchlight will do no harm, and you may see the smaller, darker (and virtually glow-less) male mating – perhaps even several on one female!

    You may also spot larvae, particularly on dark, moonless nights. They glow much more faintly, and only intermittently, for a few seconds at a time. They are also not worm-like but have segmented bodies and six legs at the head end, quite similar to the adults. They do, however, sometimes help themselves along with their tails when moving, which makes them look a bit like caterpillars. You are more likely to see them on vegetation, searching for snails, than in the same areas as the glowing females. It is important for the survival of the glow worm to find the sites where the larvae live, since only about one per cent of its life is as an adult. Comparatively little is known about the preferred habitat of the larvae, so reports of them are always welcome. They appear over a longer time span than the adults, supposedly between April and October – probably whenever conditions are right for snails and slugs.

    Click here for some more information (FAQs) about glow worms and larvae.

    How they glow

    The light from glow worms is cold, and is a form of bioluminescence. It is far more efficient than most light sources we are familiar with. It is caused when a molecule called luciferin is oxydised to produce oxyluciferin, with the enzyme luciferase acting as a catalyst in the reaction. Adult Lampyris noctiluca do not have the same control over the oxygen supply of many fireflies, which can switch their lights on and off in an instant, and take minutes to switch on or off. Larvae, however, have smaller light-emitting organs and can twinkle briefly. Male glow worms have the same ability, but it is rare to see them glow.

    Management of sites

    Some people have asked about the conditions for encouraging glow worms or breeding them. If you don't have glow worms nearby, there is no way of attracting them, any more than planting bamboo will attract pandas. But if you do have glow worms, you will want to know how to keep them. We still do not know why some colonies die out even though there are no obvious factors such as destruction of habitat, use of pesticides or herbicides, or strong artificial lighting of the site. Glow worms need a supply of small snails as food and therefore a patch of vegetation where they can find the snails. They also need a comparatively open area where the females can display to attract a male in June, July and August. As they retire into the ground during the day, high mowing does not appear to affect them unduly and very long grass may actually not be very suitable. It is far better to keep a site under control than to let it become overgrown.

    However, my feeling (in discussion with a keen observer, Linda Worrall of Barrowden, Rutland) is that the best cutting regime is not to cut at all during the glowing season from the beginning of June till the middle or end of August. If cuts are vital they should be restricted to high cutting, so as not to get down to the insects which will be down in the understorey. A certain amount of hay lying on the top is preferable to raking it up, which would probably disturb the glow worms, but what you have to avoid is cutting in wet weather which will produce a thick mat of clippings that even the most determined glow worm will find it difficult to climb through at night.

    The females may appear on footpaths and there is therefore a danger period during summer if the path is heavily used in the late evening while they are emerging to glow. There is not much that can be done about this other than getting people to walk in single file.

    As for breeding them, this has been done with varying results. Even under favourable conditions there may be a high mortality. Do not carry home glowing females hoping that they will lay eggs, or even catch a female that has apparently been mated in the hope of hatching a brood. It is better to leave them in the wild.

    Are glow worms declining and if so, why?

    This is a tricky one. Probably their numbers are on the decline, and on many individual sites they certainly have vanished, but with so little accurate historical information to go on, it is hard to put numbers on it. Similarly, we can’t be dogmatic about the reasons for any decline. If you study one site over a period of years you find that numbers can vary wildly from year to year, and from place to place on the site. It's a mistake to assume that high numbers are the norm, and be concerned about a decline when numbers are lower – you need to look at the long-term trend. However, Tim Gardiner has recently (2020) published an important paper which analyses data recorded using a standard method from a number of sites in Essex between 2001 and 2018, which you can read here.

    The obvious factors which suggest themselves are:

    Changes in habitat When you go to the sites in the historical county-by-county records (see below) you find that many have now been built on or have been ‘improved’ in some way (eg an open space has now been ‘parkified’ by the removal of weeds.

    Use of pesticides and herbicides This is bound to have an effect on the prey of glow worms and on the insects themselves.

    Artificial lighting This has increased in extent enormously since the 1960s and few landscapes are now free from light pollution. Even in country areas householders’ insecurity lights – pardon me, ‘security’ lights – blaze across wide areas. There is no doubt that male glow worms are attracted to artificial lighting of any colour and this must distract them from finding females. Even moth traps set up by entomologists themselves can be a factor. But without a detailed long-term site survey with accurate and consistent before-and-after results there is no firm evidence that this does cause a decline. However, most glow-worm sites are in dark areas and this suggests that lights do cause a decline.

    Changes in land use Much of what was open downland (such as on the Chilterns and South Downs) is now no longer grazed by sheep, allowing them to become increasingly overgrown. Glow worms prefer open areas to dense undergrowth. The increasing amount of set-aside land may be a positive change in the short term, if there are glow worms nearby to colonise the area.

    We have become concerned that sheep grazing might not be as beneficial as we thought. In the past, both sheep and rabbits would keep the grass short, but rabbits are now often shot, leaving it all to the sheep. Sheep’s urine may be bad for snails, removing the glow worms’ food supply. We need to find sites where there are known changes in management and reliable counts of glow-worm numbers, to see if there is anything in this.

    Parasites On some sites, parasitic beetles may affect the population of glow worms. John Horne has written a report detailing his work showing how the small beetle Alaobia scapularis is parasitic on glow-worm larvae at a site in Hampshire. Read it here.

    Other UK glow worms

    Virtually all the glow worms seen in Britain are Lampyris noctiluca. There is another species of glow worm in Britain, Phosphaenus hemipterus which is vary rare and until recntly seen only in parts of Sussex and Hampshire. A specimen was seen in 1995 in Sussex, the first since 1961, and a small colony exists on a private nature reserve in Hampshire. In 2009, a new site was found near Tunbridge Wells, and in 2010 sightings were reported in North London. The adult female is only 5-7 mm long compared with 15-25 mm for Lampyris (though bear in mind that the Lampyris larvae are often only a few millimetres long). Furthermore, Phosphaenus does not glow – so if the ones you see glow, they are the common Lampyris noctiluca. Should you suspect that you have found Phosphaenus please contact either Robin Scagell or John Tyler immediately so that they can come and verify the identification. Please do not try and catch or kill Phosphaenus if you do see it. For more information, see this article by Raphaël de Cock, John Horne and John Tyler.

    Raphaël de Cock has contributed a page showing how to identify the three main European species: the common glow worm Lampyris noctiluca, the lesser glow worm Phosphaenus hemipterus and the firefly Lamprohiza splendidula,found in mainland Europe.

    Is it really a glow worm?

    There are other creatures that emit some luminescence, including caterpillars and centipedes, and fungi can also glow. See here for a photo of a geophilomorph centipede, for example.

    Another cause of false reports of glow worms is actually light reflected from shiny leaves, dew or litter. So please check that what you see really is a beetle with the light coming from the final tail segments.

    Finally, we get occasional reports of fireflies in Britain – that is, insects glowing brightly while in flight. As far as we know these do not exist in the UK, and it is probable that the reports refer to other flying insects seen in light beams. True fireflies swarm around a clump of bushes or in a glade or wood. If you do come across fireflies in Britain then make every effort to catch and keep one and let us know immediately. Fireflies are found in some places on the near Continent, and for a few reports go to the International section.

    Glow worm evenings and walks 2024


    An increasing list for 2024, but we are keeping our eyes peeled for more events and more will be added as we hear of them. If you know of further events being planned for 2024, please let us know. Warning: Some of these events may be listed as finishing at 10.30 pm, yet in midsummer glow worms may not even start to glow until that time. So if you are taking children, bear in mind that the events may finish later than advertised. NR = Nature Reserve

    Date Location County Cost Weblink
    Wed 12 June Penrhyndeudraeth Gwynedd £5 Creatures of the night 3 Tickets, Wed 12 Jun 2024 at 20:45 | Eventbrite
    Sat 15 June Princes Risborough Bucks £5 adult. £2.50 child. John Tyler - Conservation
    Wed 19 June Steyning Sussex £6 adult. Under 18s free. Glow-worm Hunt (guestlist.co)
    Thu 20 June Kippax West Yorkshire £10 adult, £6 children Glow-Worm Walk Tickets, Multiple Dates | Eventbrite
    Fri 21 June Pensthorpe, Fakenham Norfolk £15.95 Category Grouped Products (pensthorpe.com)
    Fri 21 June Tunstall Suffolk £5 Evening Walk: Nightjars and Glow worms (DZC2986) Tickets, Fri, Jun 21, 2024 at 9:00 PM | Eventbrite
    Sat 22 June Princes Risborough Bucks £5 adult. £2.50 child. John Tyler - Conservation
    Thu 27 June Lewes Sussex £20 Glow-worm Evening Tickets, Thu 27 Jun 2024 at 20:00 | Eventbrite
    Fri 28 June Tunstall Suffolk £5 Evening Walk: Nightjars and Glow worms (DZC2986) Tickets, Fri, Jun 28, 2024 at 9:00 PM | Eventbrite
    Fri 28 June Kippax West Yorkshire £10 adult, £6 children Glow-Worm Walk Tickets, Multiple Dates | Eventbrite
    Fri 5 July Pensthorpe, Fakenham Norfolk £15.95 Category Grouped Products (pensthorpe.com)
    Fri 5 July Beaconsfield Bucks Donations Events (google.com)
    Fri 5 July Ketton Leicestershire ? Leicestershire & Rutland Bat Group: Bats and Glow-worms walk | Leicestershire and Rutland Wildlife Trust (lrwt.org.uk)
    Fri 5 July Y Graig Nature Reserve Denbighshire £5 Glow Worms Walk at Y Graig Nature Reserve (with Ramblers Cymru) Tickets, Fri 5 Jul 2024 at 21:30 | Eventbrite
    Tue 9 July Stroud Gloucestershire £7 adult, £3 children Glow Worm Walk — Stroud Valleys Project
    Thu 11 July Lewes Sussex £20 Glow-worm Evening Tickets, Thu 11 Jul 2024 at 20:00 | Eventbrite
    Thu 11 July Magor Gwent £15 non-members, £10 members Magor After Dark Tickets, Thu, Jul 11, 2024 at 9:15 PM | Eventbrite
    Fri 12 July Salcombe Devon £2 South Devon National Landscape | Life on the Edge Glow worm hunt (southdevon-nl.org.uk)
    Fri 12 July Kippax West Yorkshire £10 adult, £6 children Glow-Worm Walk Tickets, Multiple Dates | Eventbrite
    Sat 13 July Hook Hampshire £4 Local Volunteers Event: Glow Worm & Bat Walk at Bartley Heath Tickets, Sat, Jul 13, 2024 at 10:00 PM | Eventbritee
    Sat 13 July Gloucester Gloucestershire Donations welcome Hill Walk: Glow worms & Bats | FoRH (forhill.org)
    Sat 13 July Broadland Country Park Norfolk £5 Night Safari Tickets, Sat 13 Jul 2024 at 21:00 | Eventbrite
    Thu 18 July Westbury-Sub-Mendip Somerset £5 adult. Under 16s free. Wells and District Wildlife Group (wdwg.org.uk)
    Fri 19 July Swanage Dorset £6.00 Stars in the Grass: Glowworm Walk | Durlston Country Park
    Sat 20 July West Bexington Dorset £7.00 The Great Glow Worm Hunt 20th July Tickets, Sat 20 Jul 2024 at 21:30 | Eventbrite
    Thu 25 July Hazel Hill Wood, Salisbury Wiltshire £8 or donations Bat and Glow Worm Night Tickets, Thu 25 Jul 2024 at 20:30 | Eventbrite
    Thu 25 July Swanage Dorset £6.00 Stars in the Grass: Glowworm Walk | Durlston Country Park
    Sun 28 July Hodnet Shropshire Free Annual Glow Worm Walk – 28th June – Hodnet.org.uk
    Thu 1 August Westbury-Sub-Mendip Somerset £5 adult. Under 16s free. Wells and District Wildlife Group (wdwg.org.uk)
    Sat 10 August West Bexington Dorset £7.00 The Great Glow Worm Hunt - 10th August Tickets, Sat 10 Aug 2024 at 21:30 | Eventbrite
    Wed 21 August Lowestoft Norfolk £6 Glow Worm Evening Walk (ECC2806) Tickets, Wed 21 Aug 2024 at 20:00 | Eventbrite

    How you can help – the survey and your privacy

    If you have found glow worms, please let us know where you saw them as it will help us to chart the existing numbers and geographical distribution for future reference. An accurate grid reference to the site is really helpful to us, and online maps make it a simple matter to find it. We are now storing data on the iRecord system set up by the Biological Records Centre, so data will be held permanently for future use. Though records can be viewed by anyone who registers with the site, you are now able to 'blur' the accuracy to which anyone can view your location. We strongly recommend blurring to 1 km, which will avoid anyone identifying your home. We do not give out details of private sites to the public, so please do not worry that you will get people coming round to your garden at the dead of night to see the glow worms! Link to the online form

    You need not give your personal details if you don't wish to, and the data collected is used only for the purpose of wildlife recording – we don't use our database for any other purpose, and certainly not for any mail shots.

    If you would like to take part in the survey, it’s probably best to start by finding glow worms on a known site (on public land) so you know what to look for. See the county lists for places where they wre seen in the past, or for recent reports look at the blog. Then you could look around for similar sites in your area. Old railway lines are ideal sites, but any unimproved grassland (that is, unimproved by farming techniques, and with a variety of different vegetation) is worth a look. Go along after dark, with someone else for security, and take a torch to prevent you falling down rabbit holes and to help you make notes. (Avoid very bright lights or those fluorescent camping lights that destroy night vision.)

    Glow worms start to shine as soon as it gets properly dark, which means around the time you can no longer see colour in the landscape by natural light. Count the glows you see (usually the adult females). If you plan to survey on several occasions it is a good idea to develop a standard route so that you are always comparing the same area, even if this means missing a few. Keep notes, and draw a sketch map of the area to help pinpoint where you saw the glow worms. Then fill in the online survey form.

    The form may look detailed, but if parts of it do not apply to your site or are hard to fill in just leave them blank. Please give as accurate a site location as possible. It is important that we know exactly where glow worms are to be found so that changes can be monitored over the years.

    Link to the survey form

    Historical sites county by county

    The first national survey of glow worms was carried out by the late Anthony Wootton of Country-Side magazine (the journal of the British Naturalists’ Association) during the 1970s. Members of the BNA were asked to send in records of sightings old and modern, and these were published in some detail. For a detailed set of these records, together with some more modern sightings that have been reported to me, click here. It would be very helpful if people could revisit the old sites during the glowing season, to help establish any decline (or indeed increase) in numbers.

    Publications about glow worms

    John Tyler has published a book that describes what is currently known about glow worms, and gives more information on how to find them. John has made a full survey of the literature on glow worms, and much of the information in it has never before been published in this country. It is fully illustrated in colour. By publishing it privately he has kept the costs down. The new, fully revised edition, published April 2002 (76 pp paperback, A5 format), costs £11.50 post free. For a copy please write to John Tyler at 26 Bridge Street, Great Kimble, HP17 9TN, enclosing a cheque for £11.50 made payable to John Tyler. A few copies of the first edition (64 pp, published 1994) are still available at £5.00 post free, or you can read the text-only online version completely free.

    Nick Moyes said of the first edition: ‘Excellently researched and privately published. Superb illustrations of all stages of their life cycle’ and who are we to argue.

    For a much older account of glow worms you can now read online a translation of a classic chapter about the glow worm by the great French naturalist and writer Jean-Henri Fabre. The chapter is available in the original French

    Silent Sparks: The Wondrous World of Fireflies by Sara Lewis is predominantly about fireflies, of course, but also makes reference to glow worms both in Europe and elsewhere. While the biology and behaviour of fireflies differ from those of our own glow worm, there are many similarities, and anyone who is interested in glow worms will find this book fascinating. You can find a full review of the book on the survey Facebook page.

    Books about surveys
    Malcolm Jennings of the Croydon Natural History and Scientific Society has published the results of experimental work carried out at Riddlesdown in Surrey into the variations in numbers of males and females in different areas of the site compared with temperature, and also the attractiveness of different coloured LED lures to males. You can purchase a reprint of the paper (Glow-Worm Field Experiments and Surveys 1992-2008, 24 pp) for £3.50 plus £1.00 p & p from CNHSS, 96A Brighton Road, South Croydon, CR2 6AD.

    Tim Gardiner, who as mentioned below is studying Essex glow worms, has now produced a book, Glowing, Glowing, Gone? The Plight of the Glow-worm in Essex. It presents the results of his standardised survey in Essex, one of the first serious attempts in Europe to combine analysis of the distribution of glow-worms throughout a geographical area, with long-term monitoring of abundance to determine whether they are declining across a range of sites. The book is written with both amateur naturalist and professional ecologist in mind and is a fairly easy read. The book is A5 format and is 80 pages long with colour photographs. More information including a look at the front cover can be obtained from the BNA website.

    Glow worms under threat

    Colonies are still under threat. Tony Haywood reports: On the 20th June 2005 I reported 24 glow worms at a site near Stafford. A visit last night to the site revealed a closure of the footpath/cycle-way. Repairs to holes in the path. It seems they have taken a sledge-hammer to crack a nut and have decimated the colony. Large areas of the grassy area containing nettle, rosebay and the habitat has been bull-dozed. Large piles of earth are ready to be spread, and will probably cover what remains of the colony. 4 glowing females were there last night, they are in the path of work for next week I assume. If someone had said, "I know where there is a colony of glow-worms, let's go and destroy it" they could not have been more accurate. 

    Unfortunately, glow worms are no better protected than, say, woodlice. But local authorities will often make efforts to protect the colony if they know it is there, because of the great appeal of glow worms. However, you can't assume that they know about a colony. If you know of any colony in a similar situation, it is a good idea to advise the local council or the county conservation officer of its existence, as they should be consulted before any work is carried out. They may also need advice on how to protect the colony, in which case please refer them to me. 

    In fact, Tony has now reported: The head conservationist for Stafford county council made an immediate visit to the site and stopped work on the footpath. Damage limitation was achieved. I await next year's season with hopefulness.

    Update June 2009: Tony reports that the colony has recovered, and 25 glows were seen.

    Tidy churchyards = no glow worms
    Simon Frogley has been studying the glow worms in the churchyard at Overton in Hampshire. He says:
    They are down in number and size from 2002/3. In 2002 I often counted over 90, and once 120 on any one evening. This year (2005) the maximum I've seen has been 47. However, I've been working with the vicar to try and get the policy changed there – did a TV interview with him for Meridian and wrote an article for the parish magazine – it has become so tidy there, last year was the worst, that there are few places left for snails or larvae. The best area for them now is a bank where the grass is left, so that is where they are this year (for the first time in any quantity) but there is strong street lighting above them there. Anyway, the vicar is seeking support from parishioners to provide more cover in the areas that they used to favour, so that might help.

    We heard in 2010 that an area has been left unmown in the churchyard and by mid June glow worms were already in evidence.

    The churchyard at Uplowman in Devon has suffered a similar fate. In 1992 we had reports of about 100 glow worms visible there. Our correspondent writes: 'The churchyard used to have a huge population until the locals decided it would be a good idea to tidy it up by spraying and using strimmers. Now down to single figures'. Only four were seen in July 2010.

    You might think from the above that it is a bad idea to mow an area where glow worms are seen. However, they are equally at risk from lack of management. An area left to its own devices will in due course become a tangle of brambles and other vegetation. The best management is to allow a mosaic of weedy areas and shorter grass where the females can be seen. See the remarks above for management suggestions.

    Glow worms at Broxbourne Woods Basil Ezzat writes:   Tree felling and widening of the forest track within Broxbourne Woods (Ordnance Survey grid reference TL338082) have taken place through the glow worm habitat. The part of the woodland with the glow worm habitat is privately owned. The land owners have used machinery to excavate the top soil and using large rollers to compact the subsoil. The glow worms don't stand a chance.
       The land owners were fully aware of the location of the glow worms as they allow a conservation group run by Herts Count Council's Countryside Management Service to manage the vegetation for the benefit of the glow worms annually.
        Can you highlight that anyone coming to Broxbourne Woods is likely to see greatly reduced numbers.

    It may be that if this has happened outside the glowing season, at a time when some of the larvae may have been in the surrounding woodland rather than where the glowing females appear in summer. Some may have survived the devastation, though the glowing females may well appear in different places from before. Counts this year will be very important.

    Glow worms – the Movie, and pictures of glow worms

    Christopher Gent has produced an excellent 10-minute video about glow worms which you will love. You can view it online here.

    Oliver Gent (no relation) has featured the population of glow worms at Arnside Knott, Cumbria in his video which you can view here.

    You can see a few pictures of glow worms and colonies in our gallery.

    And here's a 10-minute video by the then 10-year-old Rudi Bright and his brother:


    There are also some other videos online. This one by Robin Scagell shows a larva feeding on a snail, plus some views of glowing adult females. John Hume has taken a video of a pair mating at Ellerburn Bank, Yorkshire. Notice how at the end the female is starting to make her way down into the undergrowth, still glowing and carrying the male with her! http://vimeo.com:80/5153213

    This video by Robin Scagell shows larvae seen by day, searching for a spot where they can pupate.

    Glow-worms in popular culture

    There are many references online to poems that feature glow worms, and other literary references, and in due course I will collect some here.

    Thomas Hardy, famous for his novels about 19th century Wessex (mostly the present county of Dorset), refers to them in his book The Return of the Native, which though published in 1878 refers to the 1840s–1850s.

    In Book 3, Chapter VIII, he sets a scene where two men are playing dice for high stakes in the heathland as twilight falls and As their eyes grew accustomed to the darkness they perceived faint greenish points of light among the grass and fern. These lights dotted the hillside like stars of a low magnitude. Determined to continue their game, one man went hither and thither till he had gathered thirteen glowworms – as many as he could find in a space of four or five minutes.... It happened to be that season of the year at which glowworms put forth their greatest brilliancy, and the light they yielded was more than ample for the purpose, since it is possible on such nights to read the handwriting of a letter by the light of two or three.

    Note that the glow worms were not so plentiful that they could be gathered quickly, but their abundance is similar to that of a good site today. Even in the 21st century I have occasionally seen glow worms so densely scattered that, had I wished, I could have found 30 or 40 within the same space of time.

    Dorothy Wordsworth, sister and constant companion to her more famous brother William, the poet, makes several interesting references to glow worms in her diaries at the beginning of the 19th century. I have collected her references and commented on them on this page.

    Heather Joyce has written a great song about the glow worms that appeared in her garden in France, and you can hear her sing it here.

    Helen Swan has produced and presented a whole radio programme about glow worms, including poems and Heather's song, which you can hear online.

    John Tyler, whose book mentioned above is the definitive work on glow worms in the UK, has also contributed a short piece to a book called Summer: an Anthology for the Changing Seasons, published by Elliott & Thompson in May 2016.

    Other people interested in UK glow worms

    The UK national recorder for glow worms is Stephanie Skipp. As reports of glow worms sent to this site are now made directly to iRecord, to which Stephanie and indeed Wildlife Trusts and other interested bodies have full access, please report just to this site, using our specific glow-worm reporting form on iRecord.

    The leading glow-worm expert in the country is John Tyler. He was previously warden of a wild fowl reserve in Sevenoaks, and is now a freelance naturalist.

    John Horne has made detailed observations of glow worms at a nature reserve at Bursledon, near Southampton, which has both common and lesser glow worms.

    A continuing survey of Essex glow worms is being carried out by Tim Gardiner of the Environment Agency. Click here to download a copy of the report in Word 97 format (260 kb).

    Dr Alan Stewart at the University of Sussex is investigating 1) Visual sensitivity and mate searching behaviour of male glow-worms, 2) Factors affecting length of life-cycle and 3) Aggregative behaviour and group feeding in early instar larvae.

    Dr John Day of the Centre for Ecology and Hydrology is a molecular biologist who is interested in the DNA of glow worms and the genetics of bioluminescence. He publishes Lampyrid, a journal devoted to the understanding of fireflies and glow worms. Some papers from this are now available as PDF files, including an important paper on the status of glow worms in England which you can access here.

    Trevor and the late Dilys Pendleton have been carrying out a very intensive survey of a site at Clipstone Old Quarter in Sherwood Forest. Their website is a mine of information on their surveys and on the appearance dates throughout the season of females, males and larvae.

    Dissertations Two useful and important dissertations on the effect on glow worms of light pollution have been produced by Stephanie Bird (2008) and Rhian Bek (2015). You can access them here:

    Does light pollution affect the ability of the male glow-worm, Lampyris noctiluca, to find females through phototaxis? Stephanie Bird 2008
    This investigates the numbers of male glow worms attracted to artificial lures on a prolific site in 2007. Numbers at the site have declined since then, and I believe that the large numbers seen in 2007 (and 2008) were abnormal and have now returned to their usual levels, with around a dozen females seen on a typical night.

    Investigating the impact of artificial night lighting on the common European glow-worm, Lampyris noctiluca (L.) Rhian Bek, 2015.
    An experiment carried out at Great Orme into the effect of different types of streetlight on male glow worms.

    International reports and surveys

    Though our survey is really intended only for the UK, we are happy to receive reports of both glow worms and fireflies from other countries and will keep the records online. We do receive requests from other countries for information and it may come in useful in the future.

    We are delighted that a national glow-worm survey is now under way in France. Called the Observatoire des Vers-luisants (French Glow Worm Observatory), it has been set up in association with the CNRS and in partnership with many other French organisations. We have already cooperated by sharing records of glow worms in the Channel Isles. You can find their survey page at www.observatoire-asterella.fr/vers_luisants/.

    A survey of Spanish glow worms and fireflies is now under way, with extensive pages of information about glow worms in Spanish. See http://www.gusanosdeluz.es/ for more details.

    "I found this glowing critter in my backyard...." If you are in the US, sorry, we can't help you identify it but we know a man who can. Prof. James E Lloyd, Dept of Entomology, Bldg 970, Hull Road, Univ. of Florida, Gainesville FL 32611 has kindly agreed to answer such queries and you can contact him via his secretary. You can read some of his firefly newsletters online at http://firefly.ifas.ufl.edu/. Click here for a news story about Lloyd from the University of Florida.

    Someone who is interested in glow worms in Belgium is Raphaël de Cock, who hopes to carry out a European survey. He is interested in the reasons why glow worms do glow, and believes that it may have originated as a warning mechanism, like the bright colours of some insects (aposematism). Contact him here or visit his website: http://lifesci.ucsb.edu/~biolum/forum/rdecock2.html.

    Peter Stallegger of Association Faune et Flore de l'Orne carried out a survey of glow worms in Normandy in 2002. Visit his website at http://monsite.wanadoo.fr/verluisant for details and maps of where they were to be seen.

    Around Zurich, Switzerland, Stefan Ineichen is an urban ecologist investigating the survival of glow worms in the country areas around the city, and even in cemeteries and gardens within Zurich itself. With financial support he has started a Glühwürmchen Projekt which is using the insect ‘as an attractive flagship species to improve habitats and to get people connected with nature.’ He is studying the factors which affect the survival of the glow worm, and would be pleased to hear from anyone who wants to help. We look forward to seeing the website which he is preparing.

    A survey in the French-speaking part of Switzerland was carried out 2001 by Centre Suisse de Cartographie de la Faune – contact Yves Gonseth for details. It was publicised through the magazine Energie-Environnement which is distributed free of charge to every French-speaking Swiss – about 880,000 people. The results were published in the December issue of La Salamandre; 900 observations were received from around 500 people. Some have seen glow worms at 2000 metres in altitude in the Alps. Click here for a more detailed report and map.

    There is also a survey being carried out in Germany. Go to http://www.lampyridae.lima-city.de/ for full details in German.

    You can find a wealth of information and research about US fireflies on the web pages of Terry Lynch. Find them at http://www.byteland.org/firefly/firefly_notebooks.html. This site gives masses of information about the rearing and preservation of the US firefly, Photinus pyralis, as well as many links for further info.

    Fireflies are also common in Portugal, where Gonçalo Figueira runs a investigation about them and other bioluminescent forms. More details on his blog (in Portuguese).

    There is an excellent firefly page compiled by Donald Ray Burger in Houston, TX, USA, with many links. Find it at  http://www.burger.com/firefly.htm.The Animaltrek site also has links to firefly pages.

    Many British people say that their only encounter with fireflies has been in Italy, but there is no firefly survey in that country. However, interest is being raised by Giuseppe Camerini, and there is now a website devoted to fireflies in Italy, at https://www.lampyridae.it/en/firefly-watching/.

    Chip Fesko has contributed a poem about the fireflies he saw as a child which may hit an old memory with others.

    In Nepal, Prem Bahadur Budha is researching fireflies but can find very little literature on the subject. If you have an interest in Asian firefly species please make contact directly. See his message on the International page.

    Further information

    Please contact me if you want to know more about glow worms. I am always happy to hear of other surveys and to see people studying glow worms.

    Site updated 10 May 2024.

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