1992 Glow Worm Report

Records of Lampyris noctiluca in Britain

This is the second full year of the glow worm survey. Although it is far too soon to be certain of anything, interesting facts have started to emerge. The long-term goals of the survey are to discover what factors affect glow worms, so that we can make sure that they continue to thrive in this country.

The survey is mostly being carried out by ordinary members of the public who happen to see glow worms or are keen on finding them. Probably very few would describe themselves as naturalists, though a number have an amateur interest in wildlife. It is easy to become enthusiastic about glow worms, which lend enchantment to summer evenings.

In the first full year of the survey, 1991, reports were received of over 250 glow-worm sites throughout Britain. More reports trickled in, and the number of known sites where glow worms were seen in 1991 is now 267.

1992 began with an item on Radio 4’s Natural History Programme in which I reported on the results of the 1991 survey, and suggested that anyone interested in looking for glow worms in 1992 should write in. The aim would be to survey old sites, to see to what extent glow worms still remain there. The late Anthony Wootton ran a survey in the 1970s through Country-Side magazine (Journal of the British Naturalists’ Association). This provided a large number of sites throughout the UK where glow worms had been seen up to the early 1970s. I believe that subsequent attempts to locate the original reports have failed, though maybe they are sitting somewhere waiting to be analysed. (Would anyone be interested in following this one up?) To the Wootton list, I added sites of which I had been told in recent surveys.

I did not realise what an avalanche this would trigger. Eventually, the BBC sent on a batch of 330 letters, and more trickled in after that! With the help of some kind friends, these people were all supplied with lists of sites in their areas, plus report forms. In many cases I saddled area coordinators with the task of circulating the individual site lists.

The site lists
The Wootton survey was invaluable, but unfortunately a large number of his informants were not very precise about the location of the old glow-worm sites. I have since found that this is quite common for old records – a general location is all that is given. While this may be adequate for general population studies, it does not help us very much. Many of the willing helpers would have had some detective work to do.

At the end of the season, it became obvious that only an apparent handful of the 400 or so volunteers had actually found any glow worms.  Area coordinators sent in their few reports, disappointed that their hard work seemed to have produced so little. For reasons of extreme pressure of other work, I had to put the forms aside, adding to them from time to time as latecomers turned up. Then, much later than I had hoped, I pulled out the sheaf of report forms – and was actually amazed at how many there were!

In all, we received forms from 206 observers. They reported on a total of 248 additional sites where glow worms were to be seen, plus a number of others where they had not found any. Negative reports are still valuable, though I always point out that a few visits are needed before a site can be definitely written off. Admittedly, it would take a dedicated glow worm hunter to revisit a site often where none had been seen.

Only a few were of the ‘Wootton’ sites. The encouraging feature, however, is that the majority were sites of which I was previously unaware.  This brings the total of sites where glow worms have been seen in 1991 and 1992 to 515. In itself, this is an impressive total, and the additional data which it represents is very valuable. All those who sent in reports have provided a very useful service in the study of glow worms. Copies of all data are being sent to the national recorder for Coleoptera, Dr Keith Alexander.

Biorecs
With this volume of data, it was obvious that a mere typing out of the data would not be particularly useful and that a computer database was necessary. I have little experience with using regular databases, and in any case they do not necessarily provide all that is needed.  Fortunately, there is a program called Biorecs which has been written specifically for the recording of natural history records. Its author, Stephen Coker, provided us with two copies at a very reasonable price.  The program can do much more than record a single species, and has many useful features. In particular, it allows us to plot a map of the occurrence of glow worms across the country. The records can be chosen according to date, county, and many other details. It will run on virtually any PC, though the larger and faster models are preferable.

Note added 2001: Biorecs is no longer used, as its complexity made it hard to add records quickly. The basic data has been extracted from it, and new data are being entered into a more standard database which allows exports to other software.

The year’s news
This report takes the form of last year’s, in that just some individual reports and observations are picked out for comment. In fact, virtually every report has some interesting feature, and the more records we get, the better.

One characteristic was noted by a number of people. Whereas in 1991, glow worms were not much in evidence until July, in 1992 they began early and finished early. The first report was from Kesgrave near Ipswich on 31 May, and the last on 28 August from Coxley near Wells.  The early trend may well have been a result of the warm spring. It may also have meant that some people missed seeing any at all: those who waited until the school holidays and the earlier dark evenings that come in August may have missed the glowing period altogether.  In 1991, by contrast, glow worms continued well into August and even September.

This was well illustrated by the numbers seen at Aston Rowant in Oxfordshire, a reliable site where over 100 were seen in mid July 1991. In 1992, however, the peak of 68 was seen in early June. By mid June the numbers had dropped away considerably. For more on this site, see the individual reports later. Similarly, John Tyler at Sevenoaks found that 16 females were already glowing on the first night of his survey, which was 1 June. He concludes that the season must have begun at least 19 days earlier than in 1991. The last female was seen on his site on 6 August, 17 days earlier than in 1991.

At this point, I should mention that I am using the term ‘glow worm’ to mean a report of a glowing adult female unless otherwise specified. The report form asked people to specify whether they were reporting females, males or larvae. It is not always a foregone conclusion, however, and some reports were quite clearly not of adult females but of  larvae. Anyone who needs more information on this should read the box ‘Females, males and larvae’.
 
 

Females, males and larvae (for new readers)
Female adult glow worms are wingless and glow brightly in June to August. The underside of their tail segments glow continuously to attract the flying males, and can be seen over a distance of 50 yards or so. They glow from dusk for a couple of hours, when they stop glowing and retreat into the understorey of the grass or some other hiding place. If they find a mate they turn off the glow soon after and do not glow again.

The males are smaller than the females and have wings which cover the segments of their bodies, without which they would look similar to females. The males can glow from their final tail segment, but usually only fleetingly. Adult glow worms cannot feed and die soon after reproducing.

Larvae are wingless and also have segmented bodies. They too can glow, but usually only for a few seconds at a time. The interval between glows can vary from a few seconds upwards. Occasionally the glow can be continuous for minutes on end and can be seen about five yards away. It is said that they do not glow on light nights (such as when there is moonlight) but this may simply be because they are harder to see on those occasions.
 

It is interesting that it is quite common for people to report seeing glow worms quite late in the year – October and sometimes November. However, these reports may well be of glowing larvae. In October 1991 I received a phone call from someone who told me of nearly 100 glow worms that evening in the lane outside. After I explained the difference between the forms the caller went out to check. They were indeed larvae. It is interesting that larvae are much more obvious at the end of the glowing season than at the beginning. Larvae seem to glow more brightly and for longer periods in autumn than in spring. This may be a result of the warmer conditions, or of a difference in their sizes at the end of the feeding season. Presumably, however, the same larvae that glowed brightly are around the next spring, so even allowing for mortality during the winter there should still be a fair number that glow. We still do not know why larvae glow anyway, and more practical work is needed.

Raising larvae
Two of us carrled out experiments to rear larvae in 1992. More and more people ask for information on encouraging glow
worms on a site, so it would seem a good idea to find out the best way to raise them, as is common for butterflies and other insects.

John Tyler used the method reported by Anthony Wootton in the 1970s, which involves raising the eggs in a glass petri dish, with moistened blotting paper to prevent them from drying out. I obtained eggs from two females, one batch being kept in a glass jar on blotting paper and one batch in a more natural environment, with soil and grass. The contents were transferred to a larger goldfishbowl style vivarium before hatching.

Sad to say, I let the blotting paper dry out too much and none of the 24 eggs kept in a glass jar hatched. Those kept in the natural environment did, however. One problem with this method is that it is impossible to keep track of the larvae. Nevertheless, some interesting data have already emerged.

The original intention was to catch two female glow worms and one male. Would the male mate with more than one female? It seems likely, but I know of nothing published about this. In 1991, I caught a female after the male had left her and she had started to retreat into the grass. I did not see them mate, however, and a couple of nights later she was glowing again.

So in 1992, I wanted to make sure that the pair mated. We caught a female with a male, and a separate female. When we arrived home, however, it was clear that the original intention was spoiled – there were two males with the female! It can be hard to see what is happening by torchlight. We had no idea which male had mated with the female. We put both males with the other female, to make sure that she would be mated.

The females laid their eggs just a day or so after mating. The successful ones hatched about a month later. One mystery which had puzzled me for some time was soon cleared up.

Many female glow worms are to be seen in locations which, while excellent for displaying their glow to passing males, are poor in food for hungry larvae. Such locations include heaps of stones, railway ballast and footpaths. One imagines that the first thing a newly hatched larva must do is to search for food. As the female apparently lays her eggs in the same place that she displays, how do these larvae ever obtain their first meal? I surmised that maybe the larvae of females in such barren areas do not survive.

When my captive larvae hatched, however, they were on the move straight away. Only a few millimetres long, they started to explore their environment. Within a few days, wherever I looked in their bowl, there was a tiny larva moving slowly around. I timed one at approximately 1 cm in 3 seconds. This may not seem much, but in a straight line it amounts to 1 metre in 5 minutes. In the course of a day, even allowing for rests and uneven ground, a larva could easily move from the hatching site to nearby vegetation where snails are to be found. I found that the larvae kept going day and night.

After a couple of weeks I was worried as none of the plentiful supply of small snails had been touched. Maybe I had the wrong type. What was sustaining the larvae, with no apparent source of food since hatching? I do not know the answer. Do they in fact gain nourishment on a microscopic scale, maybe from the slime trails of snails? There was no evidence of any of them stopping to feed. Perhaps their initial reserves are adequate to keep them going for some time. After all, it is unlikely that there will be a snail or slug immediately available.

After a couple of weeks, however, I looked in one morning to see a snail shell packed with writhing larvae, all feeding. One of their number had evidently learned the trick.

Curiously, the larvae at this stage seem to have little idea of what is expected of them. Often I would see a snail move within a millimetre of a larva, which appeared to take no notice of it. A larva could regularly be seen on the shell of a live snail, not seeming to make any effort to kill it. The classic method is to nip the snail behind its head, which injects a paralysing fluid, then to withdraw for a while and try again. Eventually the snail will be paralysed and the glow worm can start to feed. If for some reason the biting is not kept up, the snail may recover.

There was no evidence of larvae following the trails of snails, as has been suggested. I have seen larvae cross the path traversed by a snail just seconds before, without following it. The searching seems to be random. If you search for snails in the wild, they are not all that common. It seems that larvae must be able to survive for a considerable period without feeding on a snail.

What summons other larvae once one has killed a snail? Do they find it by chance – their bowl was only about 10 inches across – or is there some kind of message or scent? Even at this stage, larvae do glow, but you need to be thoroughly dark-adapted and in dark surroundings to see it. The glowing period seems to be the same as for the larger larvae – that is, a few seconds at a time with long dark periods – though the brightness is much lower.

One day I fed the snails with some lettuce leaves. I had seen no larvae for some time and I wondered if they had all died. A short while later I looked in again and found a dozen or so larvae on the lettuce leaves. Maybe they can sense the food that attracts snails and wait there for one to come along.

A few weeks after hatching I noticed that several of the larvae had mites on their backs, two or three each. These did not seem to be affecting them unduly but one day I found one poor creature with its head covered by mites. I removed it from the bowl and the next day it was dead. Curiously, none of the others had mites following this.

I saw only one other dead larva, which was curled up and shrivelled. It did not have any fungus on it, as has been reported by Anthony Wootton and John Tyler. Does the fungus kill the larvae or does it grow on dead larvae? No larvae were to be seen during December to March, but I did see up to eight feeding at a snail in mid April. Currently, in May 1993, there seem to have been more mortalities and I wonder whether it is a good idea to try to increase glow worm numbers in this way since it is hard to see what is happening. [In the end none of my brood survived.]

John Tyler reports that out of the 130 or 140 eggs which were laid in 1991, 26 larvae remain in May 1993. As this report is being written they are starting to pupate, rather earlier than those in the wild. John comments that in the last year since he has kept each larva in its own individual petri dish none have died, though it may be that mortality is greatest in the early stages anyway. He finds that he has not been able to keep track of moulting because the pupal cases disappear, presumably eaten by the snails on which he feeds the glow worms.

Studies in depth
John Tyler’s counts at the Sevenoaks Wildlife Trust have been continuing for some years. He regularly finds that glow worms appear in different areas during the season, with one area always the last to show any.  Though there was no evening rain during the count period, five counts followed daytime rain and this did not seem to put the females off glowing. Indeed, four of the five such counts coincide with peaks in the number of glowing females.

He aims to record changes in the numbers of males to see whether they mate with more than one female and whether they are affected by rain.  To do this, each glowing female was checked by torchlight and any male found was marked with white spots on the elytra – the wing cases.  They were then returned to the female.

Far more males were found in one of the four sections of the reserve, though this may be because of the order in which the sections were observed each night.

I suspect that males find the females quite early in each evening.  This is presumably why the females stop glowing after a couple of hours, and implies that if males mate more than once, they do not do so twice in an evening.

Of the 12 males marked, none was caught again, which is what happened in 1991. The small sample size makes it hard to draw any real conclusions, but it is interesting that only one male was found on any of the five nights which followed a day of rain.

John also aimed to discover if there is any way to distinguish between male- and female-producing larvae. Accordingly, he collected 30 larvae by turning over logs and so on during May. He found that they often seem to cluster in twos, threes and fours. In one case, a female larva, two male larvae and two male pupae were packed into a two-inch crevice.

He put the first seven larvae which he collected into containers with a sand floor, in case they needed to dig a pupal chamber, but all of them just pupated on the surface, so the remainder were kept in individual petri dishes lined with moist blotting paper. He measured the pronotal width – behind the head – to the nearest 0.1 mm.

He found that though there was considerable overlap, the largest larvae do seem to turn into females and the smallest into males. One larva was large enough to have become an adult but instead actually moulted into another larval instar (moulting stage). This suggests that there is also an overlap between final and penultimate instar larvae. Two did not pupate but remained as larvae.

Of the 27 which pupated, 17 were female and 10 were male. Females took about 9 days to pupate and males 12 days. The first male emerged about a week after the first female. This curious difference has been commented on before.

There is presumably some good reason why the first females to emerge have to spend several days glowing in vain, but it is not obvious.

Derbyshire
Nick Moyes of Derby County Museum attempted to find an answer to a question which has often been asked – does the same female indeed return to the same spot night after night as appears to be the case?  To find out, he marked glowing females with spots of paint on the pronotum so that they could be identified again. The paint was water-soluble and there was some doubt whether it rubbed off on some occasions.  The glow worms in question are to be found on disused railway lines around Idridgehay.

On two occasions, females were accidentally trodden on, and Nick notes that the presence of the observers on the site was clearly having an impact on individuals that were not glowing. Nick also noted that being handled sometimes apparently affected the insects, which stopped glowing or attempted to move away. A few marked individuals were recaptured a few nights afterwards, and most were in the same spot as previously.  One had moved about four feet from its previous location, however.

This ties in with other observations. My own procedure, which I commend to anyone wishing to study a site in greater detail, is to use plastic plant tags which can be written on. (I cut mine in half to make them go further!) Number each one and keep a note of the tags put out on each occasion. It is common to find the glow worm within an inch or two of the tag the next night, sometimes even having climbed it. Occasionally, however, there is a glow worm a few feet away from the tag. Except in crowded colonies, it is usually likely that this is the same individual but I could never be sure. Nick’s work suggests that this is likely to be the case.

I have never found that a female glow worm stops glowing immediately on being handled, though I have found that those I have measured are not to be seen later, though they may return the following night.  A brief inspection by torchlight, on the other hand, seems to have no effect. General natural history authors still write that ‘if danger threatens she can put out her light’ but I have never observed this.

Nick Moyes has observed that larvae, however, will often stop glowing on being disturbed. This can make locating the insect very tricky.  I suspect that as larvae glow intermittently, it is hard to be sure whether the switch-off was going to happen anyway. [Note added 2001: if confirmed, this observation seems to be at odds with the aposematism theory, that the glows are a warning to predators.]

It is inevitable that if people walk around a site, they may crush glow worms, and particularly larvae. All I can advise is to try to limit the impact of people on a site, particularly at night. I feel that the twilight period, when females are emerging from cover but not necessarily glowing, is a dangerous time. An insect that is safe during the day is much more vulnerable at this time. If
possible, do not take people to a site during this danger period, but wait until the glow worms have actually started to light up.

Individual reports
Jane Hedderwick, who lives near Bruton in Somerset, gave each glow worm that she saw a number. The most that glowed on one night was 12 on June 22. However, she reached a total of 56 separate insects between 8 June and 24 July. 27 of these were visible for one night only. She writes:

‘At the beginning of the season they only appeared to glow for about 3/4 hour each night, reappearing in exactly the same spot the next night. However, on 5 July I went out just after midnight and five [out of nine] were still glowing. I also went out to check at 2 am on 25 June and not one seemed to be lighted.

‘We also felt that they did sometimes move quite a long way – about nine feet from night to the next. We did watch some move short distances.  For this reason, some that we thought were new glow worms may have been old ones that had moved a foot or two.

One amusing little story. Last year and this, we have opened the garden to the public for charity. I was talking to a local farmer’s wife from Bratton Seymour, about four miles away, and telling her about ‘our’ glow worms. She said she had never seen one before this year when she found two on the farm. One was on a sheep’s back and the other behind a pig’s ear!’

Another study of numbered glow worms was sent in by Susan and Martin Smith of Goring near Reading. They raised plenty of support for the survey around Goring by the simple method of putting a note in the local newsletter. In all, there were 19 separate map references where glow worms were seen, mostly in Goring and Streatley.

This raised the question ‘How big is a site?’ In most cases this is not a problem, since the glow worms are found over a fairly small area. One simply quotes a map reference for the centre of the area.  But some sites are spread over hundreds of yards on a chalk down, for example. Are single glow worms in two gardens a hundred yards apart part of one original larger site? What if they are 500 metres apart? Could one male glow worm fly from one to the other? Little is known about the behaviour of male glow worms on the wing. A detailed map of the Goring/Streatley sites reveals that the glow worms were observed over a wide area, with a cluster about 2 km by 1 km and several more outlying sites where individuals were seen.  In the end, this was counted somewhat arbitrarily as seven sites.
 

A plot of the glow-worm sites around Goring and Streatley, reported by Susan and Martin Smith. The sites are spread over a couple of kilometres, plus some outliers. Only the site marked in red was recorded in the 1991 survey
Many biological records are made to four-figure grid references only.  In the case of this survey, however, I feel it important that someone should be able to return to the site in a few years time and check how things are getting on. This is why I try to get six-figure map references for the sites, which are accurate to within 100 metres.  Over the years, a site may shift its location.

One of Susan and Martin’s correspondents was Mrs Ashton who kept careful records of the 12 glow worms which appeared in her garden. The maximum number on any one night was six, one of which glowed every night from 16 July to 2 August, 18 nights. Three of them glowed for only one night.
 
 

‘Approximately a week on either side of [24 July] male glow worms were attracted to the windows of the warden’s house at the bottom of the Reserve.’ – Rod d’Ayala, Assistant Warden, Warburg Reserve, Bix Bottom, Oxon.

Such reports are of great interest as they show that males are attracted to artificial lighting. This is central to the arguments over whether or not the massive increase of street and other lighting in recent years is affecting glow worm numbers. It has been questioned whether or not males will be diverted by streetlights, since these are of a different colour and appearance from female glow worms. I asked the research station at Rothamstead (to whom such reports are sent) whether or not they had any records of male glow worms being caught in moth traps. They replied that they knew of no cases. However, I have received occasional reports of this. It would be very useful to ask moth trappers to report any instances of male glow worms being attracted in this way.

It would also be very useful to know how long the male glow worms stay attracted to the window. Do they give up after a short while or do they stay at the light until it is turned off?

It has also been noted that female glow worms can often be seen not in the darkest areas of a site but where there is some nearby lighting.  For example, in 1990 I stayed at a small hotel near Château-Thierry in France. We found 17 females in the long grass surrounding the car park, one accompanied by three males. All were to be seen in the area moderately illuminated by the car park lighting rather than in the darker areas. A search of the surrounding country road verges found no glow worms at all. Mrs V Brown of Overton, Hants, also noted in the 1991 report that the glow worms in Overton churchyard seem to avoid both the darkest areas near the church and the area closer to lighting. Obviously these are just two cases, but many other correspondents comment that the glow worms are to be found near their houses.

If female glow worms are indeed attracted to light, what could cause this? I suggest that when a female emerges from cover at dusk, she must find a place to display her glow where she will be seen by flying males. This would be the area with the largest sky area. One imagines that the trigger for the female to emerge will be a reduction in overall brightness, but then she will head for an area where the sky area, or overhead lighting, is greatest. The presence of house or other lights could influence her choice of resting place.

Do individual glow worms stop glowing because they give up, because they have been eaten or because they have mated? Though we delight to see a hillside or hedgerow full of glow worms, this is not necessarily the whole story. At Aston Rowant, Oxfordshire, a curious event took place which underlines this. My first visit in 1992 was on 6 June, when I counted 68 females over an area about three hundred metres across. I inspected each one by torchlight and found that five of them had attracted a male, and three two males, making 11 males in all. I returned on the 12th, but saw only 11 females and five males in the same area.

The big surprise came on the 27th, when I found only seven females.  Three were by themselves, two had one male each, one had three males and one had about eight or nine males! It was quite impossible to count the seething mass of insects. This raises several questions.  I have found before that in a field full of females, there will often be one that has attracted three males, while most others have none at all. Does this particular female have something about her that attracts males, was she fortuitously in the right place at the right time (maybe nearby the home of several males), or is this the sort of distribution we would expect by chance?

In the case in question, were there so few females visible not because they were particularly scarce that night, but because there was a swarm of males which had mated with most of the others within the past few days? Swarms of males were noted by Richard Elmhirst in 1912, as reported in last year’s Report.

On subsequent visits there were 25 or 26 females on 6, 15 and 26 July.  Only two males were seen, both on one female. Numbers then tailed off with two seen on my final visit, on 11 August.

‘I live on the Dyfed/W. Glamorgan border and we have a small but viable community of glow worms on a roadside verge in Dyfed. During 1991 they numered 42 glowing females but due to the dry conditions of the 1992 spring their maximum was 9.’ – H Williams, Pontardulais.

Two independent reports:
‘Female fireflies were seen on the west bank of Llyn Brianne Reservoir in Dyfed, near to “Dalarwen” at about 10 pm on Sat. June 20th. I was unable to record at what height the females were resting but my impression was that they were about four feet average above ground.’ – Jean Hemming, Llanwrda.

‘On the weekend of June 20/21 we were staying at Dalarwen and were quite excited to see glow worms (about six) on the grassy bank directly behind the house.... Nobody else has reported having seen glow worms but perhaps, like me, they didn’t realise what a rarity this would be for this part of Wales.’ – Mary Evans, Llandeilo.

We get the occasional report of fireflies but as true fireflies are not officially recorded in Britain we have to accept that these are the result of misidentifications. This pair of reports, together with Jean Hemming’s comment that the insects were resting, clearly refers to glow worms and not fireflies.

Just how common are glow worms in Wales? It is possible that there are many more sites than are recorded, given that the population density of Wales is lower than, say, Kent. Are there more sites in remote areas where people rarely venture at night, or are they all for some reason close to habitation?

‘I thought you may be interested in two sites I came across last summer while out looking for owls on an evening in June 1992. Both sites, in Newtondale, were within about 100 yards of each other with 20 to 30 in each group. Newtondale is itself in an SSSI.’ – Pawl Willett, Wildlife Ranger, Pickering.

Until Pawl’s report arrived we had no reports from the entire north east for 1992. In 1991, the only report was of two glow worms on the North York Moors Railway, a few miles away from this site. The surveys reported by Anthony Wootton in the 1970s, however, recorded many sites throughout Yorkshire and the north east. Have these glow worms disappeared or do people just not see them? In 1993 the Cleveland Wildlife Trust are to publish an appeal for reports from their members, so I hope that we will soon know of more sites. [Note added 2001 – there are still very few sites in Yorkshire and the north east.]

As in previous years, Mr & Mrs B. Jones and family of Otterbourne, Winchester, have made regular forays in search of glow worms. As well as established sites which they revisit, they have been searching for new sites. Their most prolific site is Shawford Down. ‘It is a well-used public area, managed by Hampshire County Council, mowed late summer,’ they report. In 1991 they saw 11 females and one male on this site on their one reported visit on 28 July, but the peak in 1992, on 8 July, was 62 females and four males.

They visited the down on 25 occasions in 1992. Interestingly, the population crashed in late June, rather like that at Aston Rowant.  Males were much more prevalent in the second week of observations, in mid June, but then decreased in numbers. None were found in August though a few females remained glowing hopefully. However, the number of larvae seen increased greatly during August, with 36 seen on 25 August, when all the females had stopped glowing. This is a typical pattern, well represented by their data.

The Jones family also visited St Catherine’s Hill, Twyford Down. This site, they report, is managed by the Hampshire and Isle of Wight Wildlife Trust. Part of it will be affected by the new M3 motorway, about which there has been so much controversy. It is a site well-used by local people. On 29 July 1991 they saw 13 males and seven females, while in 1992 they recorded a maximum of 67 females and 10 males on 7 July.

In addition to their visits to known sites, the Joneses also found two new sites a few hundred metres apart, both on a working railway line, which they were able to observe from bridges.

Another long-term set of observations comes from T D Knight of Littleton near Evesham. He has been recording glow worms on his local site, a nature reserve, since 1982. As well as reporting the numbers seen, he has sent graphs (below) showing the numbers seen week by week in each year, the yearly totals compared with the maximum seen in one night, and the numbers seen in each section of his regular walk (with maps to show the locations of each glow worm).

In 1992 the maximum he saw was 13 females and 1 male, on 6 July, which seems to be about average. In 1983 and 1987, only a few were seen, while in 1985, 1990 and 1991 the numbers were around 30 maximum. There is no evidence for a decline in the past 10 years. Curiously, in view of the accepted two-year cycle from egg to adult, there is no evidence for this in the numbers. Indeed, the very poor year of 1983, when only a handful of glow worms were seen, was followed in 1985 by the best year in the records, with a peak of around 30. Two years on from that, in 1987, there was another deep dip in numbers.

Does this mean that in fact the glow worms at this site take three years to reach the adult stage? Could it be that a small number of observed females is no real guide to the success of the colony and actually indicates that females are quite good at attracting mates?  Or could the deciding factor be the conditions at the time the eggs hatch out - a damp autumn could be good for the snail population and hence the success of the larvae? We have no knowledge at all of this sort of information, and anyone wishing to carry out desk research could do so with data such as that provided by Mr Knight, combined with weather records for the years in question. At the moment, I do not know of any other site which has been recorded for so many years to allow comparisons from site to site.

The variability from year to year is shown by the records made by Mrs Rosemary Mabbitt of Abberton near Colchester. ‘Generally, one to four females have been seen every year since 1975,’ she reports.  In 1990, 30 were seen, and in 1991 none.’ The maximum figure for 1992 was three. Such wide variability is common, and further suggests that the factors which affect glow worms numbers are not at all obvious.

Andrew McGeeney of Epping was one of the few to investigate one of the old sites reported by Anthony Wootton in the 1970s. He went to Highfield Wood near Hoddesdon in Herts. The original Wootton report was: Broxbourne Woods (TL 336084, 345079) sparse to numerous in damp grass and along rough ride between conifer plantations, early-mid July 1968, 1971-2.

On 7 July, Andrew found four females on the north side of a ride through the wood at TL 336084. ‘All individuals were very low down on or near the ground, in among grass and bracken,’ he reported.

Beatrice Yates of Bucklebury Common, Berks, lives in a cottage where many glow worms used to be visible, including 1991. In 1992, however, she found none despite frequent visits after dark. In a very detailed report, she quotes from a 1971 environmental survey of the common which lists a number of interesting snails and slugs in ‘wild places’.  ‘I have explored the whole area for snails which at one time were fairly abundant and attracted missel thrushes. Result of search was one very large specimen under the rockery. I do remember during the early days of our occupation – from 1970 – that both small snails and the large varieties were quite abundant.’ She also comments that the soil is much drier than in former years as a result of dry weather exacerbated by Thames Water Authority’s sinking of boreholes. The river Pang, which runs near Bucklebury Common, completely dried up in 1991 and 1992. I was pleased to see that this spring it was flowing strongly.

‘The glow worms are frequently seen from May ownards inside a large (110 ft x 50 ft) unheated greenhouse where they are usually found in the cracks between paving stones on the path. They are also frequently to be seen (June onwards) on the lightly mown grass verges and banks around the top of this large garden open to the public.’ – R R Loder, Leonardslee Gardens, Sussex.

Mr Loder tells me that the greenhouse contains large shrubs such as banana palms and that there are no signs of snails. The doors are left open during the summer months. Is this a captive population or do the larvae make their way into the greenhouse each year? Maybe the larvae that hatch inside the greenhouse do find enough slugs and snails to keep them going. A greenhouse may provide an excellent environment in which to raise glow worms.

‘I find that this year is exceptional for them (I suppose because it was an excellent year for snails – the big ones anyway). In addition to a modest normal crop in May-early June I now have a greater number than I have ever seen before. This evening (26 July) I counted over 40 in a five-minute stroll, and while a large proportion are in long grass and hard to see unless one is close by them, this suggests a density of one for about every 80 square yards. My garden is not illuminated at any point by artificial lights except very close to the main house’s windows (where I do not find glow worms).

My impression is that the greatest density of glow worms is not on large areas of mown grass, nor yet large areas of unmown grass (I have both) but within 10 or 15 feet of the boundary between the two (mown here including narrow mown paths). But this is a subjective guess.

One interesting candidate had climbed a stone wall to a height of two feet or so to be in the vicinity of a ‘betalight’ set in a doorframe.  Betalights are small capsules of pressurised tritium which give out a glow very similar to that of a glow worm in size, strength and greenish colour. I use them to mark the doors to outhouses so that I can locate them in the dark. In this case the real thing easily outshone the (rather old) betalight.’ – Francis Greene, Musbury, Devon.

I suspect that the abundance of glow worms and snails must have been a coincidence – the adults cannot eat, and one would imagine that a plentiful food supply would be more use to the larvae which are going to pupate in a year’s time. Betalights are used by night anglers, I think in order to see whether their float is still on the surface.  I regularly mistake them for glow worms at a site I visit by some water-filled gravel pits which are frequented by night anglers. I once saw what I thought was some poor glow worm floating down the Grand Union Canal, only to discover that it was a discarded betalight.

One of the new sites reported during 1992 was at Horning, on the Norfolk Broads. This is not only a new site as far as the survey is concerned, but also to the Broads Authority Conservation Officer. It was reported by Mrs Chloe Penning of Potter Heigham, who also reported a colony of 50 at How Hill Nature Reserve at nearby Ludham.

The glow worms were discovered during scrub clearance by a dyke. The area is a fen overgrown with scrub which, like several in the area, is now being cleared of the carr woodland which has grown up to return it to its former state of reed and sedge marsh. This site is rich on swallowtail butterflies, dragonflies and grass snakes.

On 26 June, 26 females were found on the site, while on 6 August there were no females but 22 larvae were seen. One wonders how many other sites which were formerly impenetrable there may be in the area.

The site at Benfield Hill, near Hove, was monitored carefully by the Benfield Hill Wildlife Trust. This is a pocket of chalk grassland within a golf course. The site was reported to Anthony Wootton in the 1970s as having 27 females, which by chance was also the number recorded in 1991. In 1992, there was a recorded peak of 42 females on 27 June. There is concern about this site since the golf club have built a club house and associated car park nearby. When the golf club subsequently applied for planning permission, the Wildlife Trust asked that the lights from the car park be arranged so that no light was visible from the site. It remains to be seen how successful this is in preserving the glow worm colony.

In the same area, Trust members reported glow worms at nearby Round Hill and also around Southwick Hill, where they are directly in the path of the A27 Bypass which is soon to be built.

Below: How glow-worm numbers varied over the season at a range of sites.

‘Our milk lady told me that she had seen glow worms glowing in her garden last summer. Llanon is by the sea in Ceredigion.’ – James Leitch, age 7, Llanon, Dyfed.

Our youngest recorder.

‘During the month of June we were intrigued to find a residential glow worm in the same locality of our garden every night about 11 pm. What made it more intriguing was the fact that we were celebrating our Golden Wedding towards the end of the month and our visitor stayed with us for the whole month. This was our first sighting for about 15 years but we do know that a nearby friend has also sighted them this year.’ – Mrs P L Evans, Clynderwen, Dyfed.

Yet another example of glow worms apparently returning to an area after years of absence. It must be the case that the glow worms are always around, but only rarely in a location where they are noticed.  What we do not know is over what area the offspring of one pair of glow worms will spread. The larvae can only walk and cannot fly, but maybe the barriers around gardens are no real obstacle to them. It would be fascinating to carry out an in-depth survey of glow worms in gardens, though this would require the dedicated cooperation of many neighbours!

Linda and Graham Worrall again turned in an excellent account of glow worms in Rutland and surrounding areas. They are the survey’s coordinators for a large area of eastern England, and their contributions are obvious from a glance at the site map. The concentration of sites around their area surely has more to do with their efforts than the real distribution of glow worms. They and their correspondents located a further 18 sites in 1992, doubling the number known in their area. Two of their 1991 sites could not be studied because of the presence of ‘New Age Travellers’! Their prime site, Barnack Hills and Holes, won the ‘Golden Glow Worm Award’ (or, at least, would have done if it existed) in 1991 with an amazing 450 glow worms on one night. In 1992, however, the site managed only a more modest 62, on 24 June. Of the sites reported in 1992, the prize goes to Firehills at Fairlight near Hastings, with a maximum of 117. To be fair, these numbers depend very much on the area surveyed. Linda and Graham note that most of their sites had lower numbers in 1992 than 1991. At Ketton Quarry, however, numbers were up from 19 to 25. There, they found females glowing right underneath and within seven yards of a sodium streetlight.

The 1991 report carried a comment from Prof. John Davenport, now Director of the Marine Biological Station on the Isle of Cumbrae in the Firth of Clyde, that he had seen glow worms at Chilworth Manor near Southampton in the early 1960s. Hazel Knight, of Havant, reported that she did see four adults in July 1992, though during daylight. The site is an experimental plot for Southampton University.

Glow worms were reported in 1991 from around Hambledon in Hampshire, perhaps more famous for its claim to be the home of cricket. Fred N. Haynes made a point of checking in the churchyard of St Peter and St Paul, where, according to local knowledge, they used to be very common. He found a maximum of nine, on 22 July. In 1991, however, the person responsible for its upkeep saw none. On 24 July when eight were seen, a local man who regularly walks his dog late at night stated that he had seen glow worms only for the first time during that week.

Fred also reports: ‘The present tenant of the sub-post office in Hambledon moved here 6 years ago. Glow worms were common in the area and one even had to be removed from the shop. In the summer of 1987 (?) an incident occurred in which, following the spraying of some of the local fields, the infant school had to be evacuated and the children sent home. Their eyes were watering severely and they had to go to Winchester (for treatment?). It does not seem to be common knowledge what was the nature of the substance being sprayed. However, there is a widespread feeling that glow-worm numbers dropped after this occurrence.’

The Devon coordinators are Lindsay and Julie Newman of Exmouth. They have a local site which they have nicknamed the Weasel Walk, between the railway line and the Exe estuary. By turning over stones, on 29 May they found a larva beginning to pupate. On 8 June it was still there, giving out a very faint light. Two days later, at 4 pm, it had transformed into a male glow worm. That night it was not to be seen, though there was another larva nearby. The next day it was there again, along with a female. On the evening of the 11th it was gone, but it was there again the next day. The last time they saw it was during the day of the 13th.

Assuming this is the same male each time, this suggests that it does not simply fly far and wide in its search for females, but instead limits itself to a fairly small area and returns to the same spot night after night. This is interesting in itself, since little is known about the behaviour of males. Though there is nothing to prevent it from flying for miles each night, it appears likely that it does not venture too far from one spot. One example does not prove the point, however, and more observations of this sort would be welcome.  Lindsay and Julie also watched a dunnock eat a female glow worm during the daytime of 17 July. They reported the last glow worms on this site on 24 August. In all, they recorded an impressive total of 112 females and 38 males on the site, with a maximum of 14 females and 14 males on 23 June.

What next?
Report forms are being sent out for the 1993 survey to all those who have responded already. I hope that people who were unable to check old sites recorded by Anthony Wootton will do if they can. All reports, whether of old or new sites, are worth having, but rather than try to cover ten sites with only a night or two at each, it is probably better to concentrate efforts on just one or two sites, getting more complete records for each. This is because the numbers can fluctuate so much: even on prolific sites, it is possible to see only three females on a particular night in July, while a week earlier there may have been dozens.

It is also a good idea to inspect each female if possible briefly by torchlight. In this way you can tell whether any males are present.  For the truly dedicated, you can put a tag by each glow worm so as to see how long each glows for and how many insects there are in total.

If you have an area coordinator, please return your forms to them by mid September each year if possible. Otherwise, please send them to Robin Scagell.

List of glow-worm sites in the UK
This list includes all sites included in the survey. The grid references are shown in numerical form, as used in the Biorecs program. They can be converted to the familiar two-letter versions by reference to the grid squares shown on the map.

In some cases, the site is in a private garden. In these cases, the grid reference has been reduced to four figures and the site name changed. Some of the other sites may be on private land, and you are requested not to trespass in order to find the glow worms.

The sites are numbered in the order the records are entered and have no other significance except that those from 001-299 were issued during the 1991 survey; those from 300-499 and 700 onwards are 1992 sites. Numbers 500-699 were issued to sites recorded before 1991.

Abbreviations: N R = Nature Reserve; G C = Golf Course

20 514672 734 YELVERTON ROCK
20 697430 735 SOUTH MILTON
20 63-51-   311 COTTAGE
20 77-64-   731 ORCHARD
20 777642 732 ABHAM ROAD
20 827443 168 SLAPTON LEY
20 896936 779 NADDERWATER
20 967888 780 WATER TOWER
20 999817 740 WEASEL WALK
20 92-96-   782 STOKE WOODS
20 94-96-   781 HUXLTOW
20 972988 784 CUTTON
21 50-32-   429 TAW ESTUARY RLY
21 537340 428 ASHFORD
21 647193 733 BARNSTAPLE
21 63-29-   737 BYDOWN LANE
21 898432 462 EASTWATER FORD
21 904438 461 WEBBERS POST
21 903480 460 BOSSINGTON
21 963445 463 HOPCOTT COMM0N
22 06-22-   306 CLARBESTON ROAD
22 12-19-   750 EFAILWEN
22 573052 756 FFOREST
22 51-67-   402 LLANON
22 69-83-   757 CWMERFIN
22 691948 759 TYNYGARTH
22 789492 729 DALARWEN
22 737719 758 YSBYTY YSTWYTH
25 338537 716 CORSEMALZIE
25 401599 717 AUCHLEAND
30 038844 739 EAST BUDLEIGH
30 042866 741 WOODBURY COMMON
30 058896 736 JONEY’S CROSS
30 27-94-   307 ASH HOUSE
30 700727 377 EASTON
30 712914 302 STINSFORD
30 77-93-   042 TINCLETON
30 950770 301 CHAPMANS POOL
31 01-15-   738 UPLOWMAN CHURCHYARD
31 04-86-   767 GARDEN
31 169066 783 LUPPITT
31 300035 066 CHARDSTOCK
31 311020 308 WAGGS PLOT
31 396367 304 MOORLINCH
31 37-93-   575 CAERLEON
31 460250 305 UPTON
31 461546 772 CHEDDAR PYLONS
31 471717 771 JACKLANDS
31 512291 310 GREEN DOWN
31 535445 309 COXLEY OLD RLY
31 593424 493 WEST COMPTON
31 505604 054 BLAGDON LAKE
31 678302 456 BRATTON SEYMOUR
31 675316 459 MONTAGUE INN
31 694322 457 CHEQUERS
31 627690 769 STOCKWOOD
31 62-86-   478 TOCKINGTON
31 710294 050 WINCANTON RACECOURSE
31 70-33-   458 COTTAGE
31 71-33-   044 HARDWAY
31 77-30-   045 BOURTON
32 411151 448 TAL-Y-COED
32 52-10-   768 PENALT CHURCHYARD
32 60-20-   751 WYE VALLEY
32 763358 773 WHITELEAVED OAK
32 763387 403 SWINYARD HILL
32 73-49-   775 BEARSWOOD COMMON
32 897334 312 TEWKESBURY
32 82-48-   774 COTTAGE
32 972028 430 CHALFORD (CANAL)
32 906331 312 TEWKESBURY
32 946384 393 BREDON HILL
32 965380 394 BREDON HILL QUARRY
33 178553 152 TYN-Y-MYNDD
33 538592 381 BEESTON CASTLE
33 698502 380 WYBUNBURY MOSS
33 995120 486 FOEL
33 943827 382 MIDDLEWOOD WAY
34 129976 487 CROPPLE HOW
35 182078 324 WASTWATER
35 328088 464 EASDALE
35 47-11-   321 MARDALE
35 45-57-   488 WARWICK HOLME
40 52-76-   713 COTTAGE
40 85-95-   313 PAGHAM HARBOUR
41 13-14-   452 GARDEN
41 173127 453 HYDE COMMON
41 229145 075 FRITHAM HEATH
41 256127 714 LONG BEECH
41 259153 390 BRAMSHAW
41 310005 449 ROYDEN WOOD
41 39-71-   760 HOE BENHAM
41 368991 450 EAST BOLDRE
41 429064 451 FURZEDOWN FARM
41 406184 710 CHILWORTH MANOR
41 487157 389 BURNETTS LANE
41 490156 391 HEDGE END
41 468277 303 OLIVER’S BATTERY
41 470250 076 SHAWFORD DOWN
41 485275 077 TWYFORD DOWN
41 495568 427 WATERSHIP DOWN
41 596798 496 THE HOLIES
41 585808 495 LARDON CHASE
41 58-80-   498 STREATLEY
41 682062 387 FARLINGTON
41 607178 715 WHITELANDS
41 63-15-   712 HAMBLEDON
41 646152 711 HAMBLEDON
41 648209 392 OLD WINCHESTER HILL
41 68-22-   730 EAST MEON
41 629324 447 ROPLEY STATION
41 627591 752 GREENACRES
41 617794 069 HARTS LOCK
41 600810 497 GORING
41 722106 709 HAVANT THICKET
41 73-53-   776 BARTLEY HEATH
41 715881 762 BIG ASHES RIDE
41 726872 763 WARBURG RESERVE
41 720880 764 BIX BOTTOM
41 722962 491 BALD HILL
41 726964 492 LINKY DOWN
41 725973 134 BEACON HILL
41 740920 499 NORTH END
41 763933 490 HAILEY WOOD
41 86-07-   701 FORDWATER ROAD
41 898168 765 HEYSHOTT DOWN
41 81-24-   388 ROGATE
41 884476 437 SANDY CROSS
41 846628 426 EDGBARROW WOODS
41 813819 473 HURLEY CHALK PIT
41 824865 470 HOMEFIELD WOOD
41 83-85-   536 GARDEN
41 88-84-   483 COOKHAM
41 884886 472 SHEEPRIDGE N R
41 886897 135 SHEEPRIDGE LANE
41 818982 468 BUTTLERS HANGINGS
41 823985 471 PARK WOOD
41 848924 469 CHAIRBOROUGH N R
41 86-94-   314 HERBERT ROAD
41 897924 467 GOMM VALLEY
41 897934 315 MICKLEFIELD
41 907165 766 HEYSHOTT DOWN
41 979180 434 BURTON POND
41 922426 445 ROYAL COMMON
41 903900 136 FLACKWELL G C
41 909919 465 HOLTSPUR
41 91-90-   484 GARDEN
41 91-90-   466 GARDEN
42 045449 401 GREENHILL
42 056447 399 ALDINGTON SIDING
42 069448 400 MUTTON BRIDGE
42 070472 395 WINDMILL HILL
42 125445 398 HONEYBOURNE
42 144432 397 NORTON HALL BRIDGE
42 159414 396 CAMPDEN TUNNEL
42 193539 753 STRATFORD RACECOURSE
42 352194 114 CHARLBURY
42 34-57-   378 CHESTERTON WOOD
42 456795 341 EASENHALL
42 478781 339 HARBOROUGH MAGNA
42 483768 340 NEWBOLD ON AVON
42 828053 007 RIFLE RANGE
42 828055 130 GRANGELANDS
42 955997 194 WAKERLEY
42 969996 327 WAKERLEY 2
42 982984 192 FINESHADE
43 139546 779 MILLDALE
43 289488 016 IDRIDGEHAY
43 28-55-   019 WIRKSWORTH
43 416408 020 STANLEY
43 889096 326 BURLEY WOOD
43 899074 316 WENDOVER WOODS
43 871297 333 KING LUD’S ENTRENCHMT
43 947006 178 BARROWDEN
43 975055 343 KETTON QUARRY 2
43 959159 317 STEPS HILL
43 955193 185 MORKERY WOOD
43 983185 332 CASTLE BYTHAM
44 819933 489 KALEPOT FARM
51 003193 411 HESWORTH COMMON
51 057156 410 PARHAM PARK
51 08-17-   409 W CHILTINGTON
51 07-21-   379 GARDEN
51 09-25-   422 GARDEN
51 02-31-   319 IFOLD
51 025349 443 SIDNEY WOOD
51 073353 443 BAYNARDS RLY
51 043430 749 STROUD FOLLY
51 087403 777 SAYERS CROFT
51 089523 748 COWSLIP FIELD
51 055867 132 HAREFIELD PLACE
51 112087 419 CHURCH HILL
51 114081 418 ROGERS FARM
51 142084 416 CISSBURY RING
51 102146 415 STORRINGTON
51 119120 420 A24 WASHINGTON
51 121134 412 WASHINGTON
51 123135 421 SANDHILL FARM
51 13-15-   414 ASHINGTON
51 145114 417 CHANCTONBURY RING
51 15-25-   703 BLINKS WOOD
51 15-25-   706 GARDEN
51 157256 704 SOUTHWATER PARK
51 165256 702 STAKERS LANE
51 162261 705 SOUTHWATER PARK
51 184224 432 W GRINSTEAD
51 103317 433 SLINFOLD
51 11-31-   424 DOWNS LINK
51 146346 454 BENLAND WOOD
51 15-39-   742 OCKLEY
51 17-38-   438 GARDEN
51 137501 746 RANMORE COMMON
51 171522 441 A24 BURFORD BDGE
51 173521 747 BOX HILL
51 175521 431 BOX HILL
51 170552 778 DOWNSIDE COURT
51 172554 440 DOWNSIDE MANOR
51 177593 444 ASHSTEAD COMMON
51 18-51-   439 BOX HILL
51 207066 423 SHOREHAM OLD RLY
51 209099 300 UPPER BEEDING
51 262079 707 BENFIELD HILL
51 267087 708 ROUND HILL
51 21-25-   435 GARDEN
51 22-25-   320 LEONARDSLEE GDNS
51 30-05-   770 RLY – ELDRED AVE
51 31-23-   425 GARDEN
51 306570 745 HAPPY VALLEY
51 300580 745 FARTHING DOWN
51 335585 744 KENLEY COMMON
51 335596 743 RIDDLESDOWN
51 346573 436 WHYTELEAFE
51 48-08-   407 GARDEN
51 489087 408 COLEKITCHEN FARM
51 465276 413 ASHDOWN FOREST
51 482524 728 IDE HILL
51 56-56-   475 GARDEN
51 530605 724 SHOREHAM
51 555644 719 MEREWORTH WOODS
51 56-56-   475 GARDEN
51 615384 718 HUTCHINSON’S BANK
51 605511 726 DENE PARK
51 62-58-   720 GARDEN
51 630550 727 MEREWORTH WOODS 2
51 64-51-   754 VALLEY DRIVE
51 690620 722 PADDLESWORTH
51 622732 386 BLUEBELL HILL
51 77-89-   406 GARDEN
51 86-12-   723 FIREHILLS
51 85-55-   477 GARDEN
51 918586 481 TORRY HILL EST
51 925562 482 WICHLING
51 929572 480 DULLY HILL
51 97-59-   479 GARDEN
52 01-53-   446 OAKLEY
52 039989 331 BEDFORD PURLIEUS
52 065987 188 OLD SULEHAY
52 170530 338 TEMPSFORD STN
52 183698 334 BRAMPTON WOODS
52 188874 336 HOLME FEN N R
52 235731 335 GT STUKELEY RLY
52 214802 337 WOODWALTON N R
52 336084 385 HIGHFIELD WOOD
52 34-56-   755 CALDECOTE
52 53-20-   474 HATFIELD FOREST
52 522366 384 WENDENS AMBO
52 718758 323 MILDENHALL
52 715762 322 MILDENHALL RNWY
52 98-43-   383 GARDEN
53 004037 180 COLLYWESTON DEEPS
53 075047 181 BARNACK
53 044125 196 ESSENDINE
53 048125 325 ESSENDINE RLY EMBKMT
53 105005 330 COLLYWESTON WOOD
53 110065 328 BAINTON
53 125017 329 CASTOR HANGLANDS
61 117346 721 LYMPNE
62 007199 485 MANWOOD CHASE
62 23-46-   053 KESGRAVE
62 477688 725 CLIFF HOUSE
63 264349 376 SOUTHREPPS COMMON
63 358165 405 MARSH FARM
63 370192 404 HOW HILL N R
 

Euroglows

What is the status of glow worms in the rest of Europe? An unconfirmed report during the year suggested that their numbers have declined in France, and that experts are blaming the spread of streetlights.  Ironically, France is much less strongly lit by streetlights than the UK and some other European countries, as a glance at a nighttime satellite photo reveals. Ten years ago, John Tyler wrote to experts in other European countries and received gloomy reports. Peter Gjelstrup of the Natural History Museum in Aarhus, Denmark, reported that although Lampyris noctiluca was very common in Denmark in the first half of the century, by 1983 there were only 10 places where it could be found, and only two where it is numerous. He blamed the lights from towns which prevent the beetles finding each other.

Similar letters came from coleopterists in Switzerland and Sweden.  Although our glow worm survey is necessarily restricted to the UK, we know of no other similar surveys abroad. It would be of interest if records of glow worms seen in other countries could be forwarded to us.

Our ‘other’ glow worm

In letters sent out before the 1992 survey, recorders in Kent and Sussex were asked to keep an eye out for the other known species of UK glow worm, Phosphaenus hemiptera. This was last reported in 1961 from Chelwood Gate in East Sussex, when two were seen crawling over stones in a rock garden. Prior to that, it was seen in the 1950s at St Margaret’s Churchyard, Buxted Park, E. Sussex. The two sites are only a few miles apart across the heathland of the Ashdown Forest.

No new reports of this glow worm have been received, either positive or negative*. It would be very useful if people in the area could make a special effort to survey the areas around the last known sites.  Regrettably, at that time the natural reaction of an entomologist on seeing a rare insect seems to have been to kill it and keep it as a specimen, so it is perhaps not surprising that no further examples have been reported.

Phosphaenus is to be found on the Continent. While females of Lampyris are brownish, Phosphaenus is described as ‘pitchy’. I do not have precise information on how brightly it glows at night, though both sexes are said to glow. As well as both sexes being smaller than Lampyris, the male Phosphaenus has very much less well developed wings beneath the elytra (the wing cases of beetles – most noticeable on a ladybird).  It is said in one reference to be flightless, though another says it can fly. One reference says that both sexes lack wings and both are brightly luminous. There is a specimen in the Booth Museum at Brighton, and it is my feeling that this specimen is all that is needed.  If they still exist in Britain, they must be preserved.

Anyone who wishes to make a special effort to find Phosphaenus may be rewarded with a very worthwhile discovery – bearing in mind the possibility of confusion with ordinary glow-worm larvae. A more detailed literature search would be a good start.

A third species, Lamprohiza splendidula, was found just once in Britain – a single one was found in a hedge in 1884 near Leeds in Kent, presumably blown over from the Continent.

* Note added 2001: Phosphaenus has now been found again in the UK at a single site in Sussex.

The Glow Worm Book

This year (1992) sees the publication of the first book on glow worms in this country. Written by John Tyler, it 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 and black and white. By publishing it privately we are keeping the costs down, but we are hoping to be able to sell copies through selected trade outlets. The cost of the book (64 pp paperback, A5 format) is £5 post free. For a copy please write to John Tyler at Tadorna, Bradbourne Vale Road, Sevenoaks, Kent TN13 3DH, enclosing a cheque for £5.00 made payable to John Tyler.

Note added in October 2000: this book is still available – and at the same price! Foreign customers please e-mail me (galaxypix@compuserve.com) and we will sort out a suitable price – in US dollars it works out at about $10 post free.