Mothematics – Some moth stats

A quick blog post as I approach my fifth anniversary of garden mothing. That’s six summers of lighting up! You’ll recall how it started.

I have recorded 457 species of moth in my garden as of 19th July 2023. Hopefully, there will be a few more this season. I have photographs of most of those species, with the exception of the marvellous Hornet Clearwing moth which I saw but didn’t net. I have also seen and recorded 37 other species on campsites, nature reserves and in holiday house gardens (New Forest, Dorset, Anglesey).

My first season began late, 24th July 2018 and I didn’t keep proper logs, but saw roughly 127 species of moth, the vast majority of which I had never noticed nor photographed before.

In 2019 I ran 272 sessions with a 40W Robinson trap and recorded 12373 moths of 315 species 125 of those were new to me. That represents 45 s/s avg, specimens trapped (and released) per session on average.

In 2020, COVID-19 lockdown year, I ran 294 sessions and had 8529 moths of 309 species, 30 of those species were new to me, and that’s a per session average of 30 s/s avg. Way down on 2019.

2021 – 288 sessions, 7608 moths of 278 species – 38 NFM – 38 s/s avg

In 2022 – 244 sessions, 7900 moths of 321 species – 64 NFM – 32 s/s avg last NFM of the year was the much hoped for December Moth, which arrived at the end of October.

So far in 2023, I have done 121 sessions, counted 3551 moths of 256 species – 32 NFM, with a 30 s/s avg. I expect to do several more sessions before the summer’s out.

If I just select out the peak season 1st of May to 30 September, things are slightly different in terms of per session averages

2023 – 1364 specimens over 64 sessions – 21 s/s – so far

2022 – 7253 specimens over 130 sessions – 56 s/s

2021 – 7194 specimens over 141 sessions – 51 s/s

2020 – 8002 specimens over 137 sessions – 58 s/s

2019 – 10966 over 128 sessions – 86 s/s

Obviously, 2019 was an interesting year, my first full season and I seemed to get large numbers of moths and quite good diversity almost every lighting-up session. Things were not so good the next summer, with a drop from almost 90 per session to just under 60, but we’d had a warm and early spring with cold snaps at night. 2021 was not like 2020 in terms of how the seasons panned out and another drop in per session average to just over 50. 2022 was half way back up between the 2020 and 2021 averages. 2023 has been quite bizarre, numbers seem to be down all diversity is heading towards the level I saw in 2021, assuming a couple of dozen NFYs turn up before the end of September.