Saturday, 19 January 2019

A few statistics for 2018

While there are few moths being seen...

A completely accurate summary can't be given until some necessary dissections have been completed and that may take a few more weeks yet, but even so it is already clear that 2018 was one of the best years ever here at Westcott.  The site is an untidy rural village garden on the clay of Aylesbury Vale with nearly all of the important tree and shrub species of the local area found within it or around its edge.  It is surrounded by other mature gardens, a churchyard, a sports-field and farmland (grazing pasture) with lots of old well-established hedgerows.  Here are some statistics for the year:

  • The twin-30wt actinic light was run in the garden on 295 nights.  Most of the missing nights were during the very cold weather between January and March, then spells when I was away in May/June and September.  During the peak summer months the 125wt MV light was also run regularly, always in tandem with the actinic.
  • In excess of 42,000 moths were caught, half as many again as the 28,190 of 2017 and significantly more even than the previous high of 33,941 in 2015.  Increased use of two traps together in 2018 will have been at least partly responsible (87 nights, as opposed to 32 in 2017).  Trap contents have always been released about a mile away so the chance of recaptures continues to be almost nil. 
  • 100 species in one night was exceeded on 26 occasions (compared to 15 in 2017). 
  • 150 species in one night was exceeded on 3 occasions (compared to nil in 2017).
  • The most diverse catch of 2018 was on 4th July (1,013 moths of circa 166 species), while the equivalent in 2017 was on 21st June (865 moths of 148 species).
  • The top ten highest individual species counts in 2018 were, in order, Setaceous Hebrew Character (1,819), Acentria ephemerella (1,798), Heart and Dart (1,571), Large Yellow Underwing (1,366), Lunar Underwing (1,190), Common Footman (1,126), Square-spot Rustic (1,077), Flame Shoulder (1,060), Pleuroptya ruralis (975) & Smoky Wainscot (874).
  • The final garden moth species tally for the year should be somewhere between 680 and 700 (the previous record was 662 species achieved in 2017).
  • At least 25 new species were added to the garden list during the year, including nine macro-moths (Pinion-spotted Pug, Oak Processionary, Jersey Tiger, Four-spotted Footman, Marbled Clover, Fen Wainscot, Obscure Wainscot, Purple Clay & Cream-bordered Green Pea).  2017 had also seen nine macros added to the list along with 21 micros. 
  • The garden Lepidoptera list currently stands somewhere between 990 and 1,000, all recorded post-millennium.

It would be very interesting to hear how others got on during the year.  If your records are up-to-date and you've already sent them to your County Moth Recorder, maybe some of you could look at producing a few statistics of your own?  Not as a comparison to those above (because not everyone is able to put in the same amount of effort and all locations are different), but against how your own site has done in previous years.  While the general consensus seems to have been that it was a much better year than normal, I do know of a few people who felt that it was, at best, rather an average one.

Dave Wilton
Westcott, Bucks


  1. That's an impressive set of statistics, Dave. I will have a go at producing a similar set for my garden, but it will take a little while.
    Based on the high number of Acentria ephemerella, I would guess you have a garden pond? When you run the 2 different lights in tandem, are they near each other or in completely different parts of the garden?

  2. Hi Steve, ephemerella can turn up anywhere, well away from water. It must be good at dispersal even though it seems to be very short-lived - less than half of those which come to light seem to survive until morning. We don't have a pond but there is a good network of ditches locally and several of our neighbours do have ponds (one in particular has a large linear example with reeds, bulrushes and flags which I think was originally created from one of the ditches).

    Our back garden isn't all that large but there is an ivy-covered wooden fence with a blackthorn/hawthorn hedge running along it which divides one part from the remainder and I can use that hedge as an effective screen when the leaves are out (it wouldn't work in winter). When I do run the two traps they are about 15 metres apart, the MV on a small area of lawn beyond the hedge underneath a gazebo which stays up for the summer, while the actinic is run on the patio in the main part of the garden (usually on top of a garden table with a white sheet over it). The collecting box for the garden MV is an 84 litre Really Useful Box with a circular hole cut in the lid, giving more capacity than a Robinson and with the advantage that it will take large egg trays without them having to be cut up. However, having a flat top means that it isn't waterproof, hence the use of the gazebo.


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