The glowworm season started earlier this year at our site near Thurgoland with the first glowworm being recorded glowing on the 30 May, after a few weeks of hot dry weather. On the following three visits, the weather was wet with low glowworm counts.
The counts and the weather started to improve towards the end of June with a count of 11 on midsummer day (they usually peak around the 21st ). I was now expecting numbers to drop, but they kept increasing with 19 on the 1st July dropping to 7 on the 8th July; it was heavy rain which they do not seem to like!
Ten days later 48 were counted in the better weather. The numbers kept up throughout July/August with a peak of 55 on the 13th September (with a possible high percentage of juveniles).
Numbers slowly fell for the next two visits to the end of September – at this stage I thought I would be counting until Christmas – but then at the start of October numbers reduced dramatically and the 2020 glowworm season finished on the 21st October.
The length of the season has been 144 days compared to 132 days in 2019. Why this is, is unclear at the moment. Records compiled by Doug Brown.
[Congratulations Doug on your persistence and stamina! Thanks to Pete Riley for the images]