Nottinghamshire Glow Worms 2022
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The Glow Worm is without doubt, one of our most fascinating insects. Famous for the ability to produce its own light, the green bioluminescence emitted by the female Glow Worm has formed the basis of countless fairy tales and folklore over centuries.

Despite still regarded by some authorities as being both nationally and locally common, this delightful beetle has been proved to be in serious decline.

The data collected by a number of local recorders over the past ten years, has helped confirm both decline and demise in Nottinghamshire's Glow Worm populations. However, getting people to sit up and take notice has proved to be rather difficult and it doesn't help when those very same authorities continue to denounce any existance of decline. 

Habitat loss through urbanisation and industrial development, the use of pesticides and herbicides in modern farming practices and the increase in light pollution, are all thought to have contributed to the Glow Worm's decline.

 
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But Nottinghamshire is fortunate in having one of the UK's largest and most famous Glow Worm colonies in the shape of Clipstone Old Quarter. For many years, Clipstone Old Quarter (located deep within the heart of Sherwood Forest) was synonymous for producing the UK's earliest larvae and females and with the 2022 glowing season only a few months away, there is much to look forward to.
 

Help monitor Glow Worm distribution - contribute your records

Members of the public can contribute to the Nottinghamshire Glow Worm Survey and we welcome any Glow Worm records from within VC56 Nottinghamshire. The easiest way to contribute your records, is by completing the simple online survey form on the right.

The form can also be used to send in any old Glow Worm records you may have, as old records are important in helping to determine a more accurate picture of Glow Worm distribution and how it has changed over time. And it is just as useful if we know where Glow Worms are not found, so please remember that negative results from a site are equally as important as positive results and will help our mapping of the Glow Worm's distribution.

Useful Glow Worm links on www.eakringbirds.com

 
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Predicting the start of the glowing season in 2022

I often get asked when the first Glow Worm will appear? Its a difficult question to answer and you would think that after monitoring the larval population of a colony for the over a decade, then I should have some idea by now. Such predictions are difficult and largely guesswork at best, but there are factors that needed to be taken into consideration.

The ability of Glow Worm larvae to find food over at least two years is one, especially during periods of prolonged dryness. In the past, Sherwood Forest has undergone periods of very dry conditions which leads to the dehydration of Glow Worm larvae. During some larval surveying in the late Summer and early Autumn of 2013, Dilys and I found that some larvae were becoming paper thin and when rain did eventually arrive on September 6th, we found larvae taking on much needed water.

The variabilities of the UK weather is without doubt the biggest factor in determining when any species will appear. Not just around the time of adult emergence, but over the course of the previous few months and probably well over the past year of larval life in Glow Worms.

 
Photograph by Martin Dale

For larvae going on to become adult this Summer, having suitable weather conditions for hunting (warm and damp) and the ability to find enough food during the previous Autumn, is thought likely to be much more critical than during the Spring, as most pre-pupation development has probabaly already taken place. We have had over-wintering larva in captivity, which never ate anything before pupation.

 
Average monthly minimum Winter temperatures 2008-2022
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    2008/09 2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22
Nov - Apr   2.80°C 2.08°C 2.35°C 3.28°C 1.55°C 3.33°C 2.93°C 3.59°C 3.46°C 2.68°C 2.97°C 3.50°C 2.55°C 3.61°C
Jan - Apr   2.80°C 1.62°C 3.67°C 2.75°C 1.05°C 3.62°C 2.45°C 2.35°C 3.50°C 2.47°C 3.41°C 3.82°C 1.92°C 3.40°C
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Date of first female   May 27th May 24th May 13th May 30th June 8th May 18th May 23rd June 3rd May 20th May 24th May 31st May 20th June 3rd May 17th
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Average monthly maximum Winter temperatures 2008-2022
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    2008/09 2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20 2020/21 2021/22
Nov - Apr   8.68°C 8.04°C 8.71°C 9.79°C 7.33°C 10.29°C 9.50°C 10.26°C 9.60°C 8.51°C 10.51°C 10.31°C 8.91°C 10.41°C
Jan - Apr   9.27°C 7.67°C 10.70°C 9.75°C 6.95°C 10.89°C 9.60°C 9.30°C 10.12°C 8.57°C 10.85°C 11.30°C 8.80°C 10.90°C
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Date of first female   May 27th May 24th May 13th May 30th June 8th May 18th May 23rd June 3rd May 20th May 24th May 31st May 20th June 3rd May 17th
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Predicting the likely date of the first female Glow Worm of any year is difficult and not an exact science by any means. But temperatures over the latter months of 2021 and 2022 seem to be very similar to that of the corresponding Winters of 2016/17 and 2019/2020, so the first female at Clipstone Old Quarter in 2022, could perhaps be expected to appear around May 20th.
     
Nottinghamshire Glow Worm records 2022

The season of larval surveys ended on May 13th, with the first survey for female Glow Worms commencing with surveys on May 10th and May 15th. The first female was recorded on May 17th, at the bottom of Section D. This is an early date, in fact the second earliest ever at Clipstone Old Quarter.

Contributors to the Nottinghamshire Glow Worm Survey 2022
  
Thanks to the following people who have sent in their survey results: Trevor Pendleton.
 
Surveyed   Site name   Grid ref   Site type/habitat   Qty   Notes   Recorder
May 17th   Clipstone Old Quarter   SK608674   Former Pine plantation and grass/scrub strip   1   The year's first female Glow Worm was found at the bottom of Section D, on a rather wet, but warm evening. Sections (in order of surveying) O,L,M,K,J,D,C,B and A were surveyed.   TP.
May 15th   Clipstone Old Quarter   SK608674   Former Pine plantation and grass/scrub strip   0   No female Glow Worms recorded during a survey for adults this evening. Sections (in order of surveying) O,L,M,K,J,D,C,B and A were surveyed.   TP.
May 13th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
May 12th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
May 11th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   3   Three larvae in Section D this evening, following rain for much of the day. Larval lengths included 20mm, 21mm and 23mm.   TP.
May 10th   Clipstone Old Quarter   SK608674   Former Pine plantation and grass/scrub strip   0   No female Glow Worms recorded during an early survey for adults late evening. Sections (in order of surveying) O,L,M,K,J,D,C,B and A were surveyed.   TP.
May 9th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
May 8th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
May 7th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
May 6th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 20mm larva recorded from Section D this evening.   TP.
May 5th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A 23mm larva was found fatally injured in Section A. Another larva was found in Section M, earlier in the day.   TP.
May 4th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   5   Five larvae found this evening, the count no doubt helped by the previous night's rain. Larval lengths and areas included  two larvae measuring 22mm and 24mm in Section A, a 21mm larva in Section C and two 21mm larvae in Section D.   TP.
May 3rd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded during an early afternoon survey   TP.
May 2nd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 20mm larva recorded in Section A   TP.
May 1st   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 30th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   2   Two larvae in Section A late evening, measuring 17mm and 22mm, were the first larvae from this section since 13/04/22.   TP.
April 29th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   3   Three further larvae recorded this evening, with the first of the year found in Section C (x2) and a single in Section D. Lengths included 15mm, 18mm and 21mm.   TP.
April 28th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   3   Another three larvae mid-afternoon, all once again recorded within a relatively short length of Section D. All of the larvae in section D have been recorded similarly Larval lengths included  22mm, 24mm and 26mm.   TP.
April 27th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   3   Three larvae recorded in Section D this evening, with recorded lengths of 21mm x2 and 22mm   TP.
April 25th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 21mm larva recorded in Section D   TP.
April 24th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   2   Despite the continuing dry conditions, a 20mm larva recorded in Section D this evening. A 25mm larva was also found in another section of this site.   TP.
April 23rd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 21st   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 16th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 13th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 16mm larva recorded in Section A this evening.   TP.
April 12th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   2   Two larvae measuring 22mm and 23mm, were found along Section D during a morning survey.   TP.
April 11th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 10th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   2   Two (live) larvae found in Section D this evening, with lengths of 22mm and 17mm.   TP.
April 9th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   2   Two larvae found in Section D. Larval lengths were 18mm and 20mm. Unfortunately, the latter larva was found freshly dead.   TP.
April 8th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 6th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
April 5th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   One 18mm larva recorded along Section D this evening.   TP.
April 4th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   3   Three larvae recorded on a mild evening, although unfortunately one 17mm larva in Section B was found dead. Two live larvae, were found in Section D, measuring 16mm and 17mm.   TP.
April 3rd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 29th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 28th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 27th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 25th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 15mm larva was found in Section D this evening   TP.
March 24th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 23rd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 22nd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 21st   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 17th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A 24mm larva was found in Section A this afternoon, but was unfortunately mortally wounded   TP.
March 16th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 15th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
March 13th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A 15mm larva in Section A, was unfortunately found dead close to the path edge, having been crushed underfoot   TP.
March 12th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A 20mm larva found along Section B this evening   TP.
March 10th   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   1   A single 14mm larva found with fresh prey item (Slug) in Section D this evening   TP.
March 3rd   Clipstone Old Quarter   SK608674   Gravel cycle path through former Pine plantation and grass/scrub strip   0   No larvae recorded   TP.
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Larval survey data 2022

Now that the larval surveying season is finally underway, the size data obtained from surveying, is now slowly starting to build. Early larvae were recorded on March 10th (14mm) and March 12th (20mm) and following an apparent reduction in Glow Worm numbers along the grass strip survey sections of A, B, C and D over recent years, it will be interesting to see what the subsequent larvae and female numbers will be during Spring and Summer 2022.
 
Fig 01. ... Glow Worm larval size ranges found at Clipstone Old Quarter during March 2022   Data correct as of 31/03/22
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    9mm-15mm larval size range   Intermediate   19mm-28mm larval size range
Section   9mm 10mm 11mm 12mm 13mm 14mm 15mm   16mm 17mm 18mm   19mm 20mm 21mm 22mm 23mm 24mm 25mm 26mm 27mm 28mm
A .. 1 0 0 1 0 0 1 .. 0 0 0 .. 0 1 0 0 0 1 0 0 0 0
B .. 0 0 0 0 0 1 1 .. 1 0 2 .. 2 0 0 1 0 1 0 0 0 0
C .. 0 0 0 0 0 1 0 .. 0 0 0 .. 0 0 0 1 0 0 0 0 0 0
D .. 0 0 0 0 1 1 1 .. 0 1 3 .. 2 1 2 1 0 0 1 0 0 0
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    9mm-15mm larval size range 60.00%   Intermediate 00.00%   19mm-28mm larval size range 40.00%
Total % .. 0.00 0.00 0.00 0.00 0.00 20.00 40.00 ... 0.00 0.00 0.00 ... 0.00 20.00 0.00 0.00 0.00 20.00 0.00 0.00 0.00 0.00
 
Fig 02. ... Diurnal Glow Worm larval size ranges found during April 2022   Data correct as of 30/04/22
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    9mm-15mm larval size range   Intermediate   19mm-28mm larval size range
Section   9mm 10mm 11mm 12mm 13mm 14mm 15mm   16mm 17mm 18mm   19mm 20mm 21mm 22mm 23mm 24mm 25mm 26mm 27mm 28mm
A .. 1 0 0 0 0 0 0 .. 1 1 0 .. 0 0 0 1 0 0 0 0 0 0
B .. 0 0 0 0 0 0 0 .. 1 0 0 .. 0 0 0 0 0 0 0 0 0 0
C .. 0 0 0 0 0 0 1 .. 0 0 0 .. 0 0 1 0 0 0 0 0 0 0
D .. 0 0 0 0 0 0 0 .. 1 2 3 .. 0 2 3 4 1 1 0 1 0 0
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    9mm-15mm larval size range 04.00%   Intermediate 37.50%   19mm-28mm larval size range 59.50%
Total % .. 0.00 0.00 0.00 0.00 0.00 0.00 4.00 .. 12.50 12.50 12.50 .. 0.00 8.25 16.50 20.50 4.00 4.00 0.00 4.00 0.00 0.00
 
Fig 03. ... Diurnal Glow Worm larval size ranges found during May 2022   Data correct as of 11/05/22
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    9mm-15mm larval size range   Intermediate   19mm-28mm larval size range
Section   9mm 10mm 11mm 12mm 13mm 14mm 15mm   16mm 17mm 18mm   19mm 20mm 21mm 22mm 23mm 24mm 25mm 26mm 27mm 28mm
A .. 1 0 0 0 0 0 0 .. 1 1 0 .. 0 1 0 2 1 1 0 0 0 0
B .. 0 0 0 0 0 0 0 .. 1 0 0 .. 0 0 0 0 0 0 0 0 0 0
C .. 0 0 0 0 0 0 1 .. 0 0 0 .. 0 0 1 0 0 0 0 0 0 0
D .. 0 0 0 0 0 0 0 .. 1 2 3 .. 0 2 3 4 1 1 0 1 0 0
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    9mm-15mm larval size range 00.00%   Intermediate 7.75%   19mm-28mm larval size range 92.25%
Total % .. 0.00 0.00 0.00 0.00 0.00 0.00 0.00 .. 0.00 7.75 0.00 .. 0.00 23.00 30.75 15.25 15.25 7.75 0.00 0.00 0.00 0.00
 
Larval survey data 2009-2022

Data gained from larval surveys conducted at Clipstone Old Quarter during March, April and May in previous years, showed a decrease in the average length of Glow Worm larvae over the time period.
We found that the average larval size from 2009 to 2014 was 20.32mm, based on the data gathered from a total of 771 larvae. The data also showed that larvae were on average, considerably larger in 2009 (22.21mm) than in any of the following years, equating to 1.89mm larger than the average produced between 2009 and 2014. This has continued to be the case and the average length of larvae in 2016 was found to be just 17.99mm, showing a decrease of 4.22mm on larval length data obtained in 2009.

The data in the table provided in Fig 02 below, is presented as (for example) 17.00mm/tL6. An explanation of this would be 17.00mm (the average larval length) / tL6 (taken from a total of six larvae) but this obviously changes daily after each survey, as the size data for latest weekly time period is continually recalculated and updated. The Spring average follows the same principle, but the average is obviously taken from the total number of larvae found that Spring period.
 
Fig 02. ... Glow Worm larval averages during Spring 2009-2022  Data correct as of 06/05/22   * means weekly average data incomplete  
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Week/period . 2009 2010 2011 2012 2013 2014 2015 2016 2020 2021 2022
March 22-31 . ..... ..... 18.03mm/tL27 21.16mm/tL6. ..... 17.90mm/tL13 .   18.44mm/tL90 17.63mm/tL28 00m..............m
April 1-7 . 23.33mm/tL3. 21.27mm/tL13 18.64mm/tL70 19.00mm/tL5. .... 18.65mm/tL24 18.16mm/tL6.   16.46mm/tL13 19.75mm/tL4 16.75mm/tL4
April 8-14 . 21.14mm/tL14 19.58mm/tL17 19.19mm/tL31 19.66mm/tL9. 17.11mm/tL9. 18.27mm/tL59 19.11mm/tL16 15.00mm/tL3     19.71mm/tL7
April 15-21 . 20.45mm/tL10 20.78mm/tL18 19.78mm/tL53 23.20mm/tL5. 18.34mm/tL34 18.62mm/tL22 20.66mm/tL8.   18.26mm/tL20 18.00mm/tL1  
April 22-29 . 23.32mm/tL25 18.74mm/tL53 19.97mm/tL39 18.77mm/tL9. 18.61mm/tL25 20.20mm/tL36 .   18.83mm/tL6* 21.66mm/tL3 21.27mm/tL11
April 30-May 6 . 22.95mm/tL20 23.20mm/tL5. 21.87mm/tL8. 20.95mm/tL22 19.85mm/tL16 21.87mm/tL21 . 17.66mm/tL15 . 19.75mm/tL4 21.10mm/tL10
May 7-14 . 22.08mm/tL17 23.25mm/tL4. ..... 22.30mm/tL10 21.62mm/tL21 21.25mm/tL4. ..... 18.22mm/tL22 ..... 19.75mm/tL4 .21.33mm/tL3*
May 15-22 . . 19.66mm/tL60 . . 21.71mmtL/8 . . 19.97mm/tL34 . . .
May 23-30 . . . . . . .   19.11mm/tL90 . .. .
. . .
Spring avg   22.21mm/tL89 20.92mm/tL116 19.58mm/tL228 20.45mm/tL66 19.52mm/tL103 19.53mm/tL169 N/A 17.99mm/tL83 N/A 19.35mm/tL44 N/A
 

The size data produced since 2010 has been remarkably consistant where sufficient data was collected, showing a variation of just 1.40mm. 2021 and 2022 data is currently not included in this. Breaking the data down further, the average size variation in three of the years since (2011, 2013 and 2014) showed variation as little as 0.06mm. If we exclude the 2009 size data on the basis of being unusually large, then an average larval size at this site would be approximately 20.00mm. The relative consistant larval sizes suggests that variations in rainfall and temperature between November and March in any year, actually had no influence on larval size.

 
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