2022 in Numbers: Westcott

As I've mentioned on here before, finding out what people think about their own mothing year is a fascinating exercise (to me, anyway!).  Each December I usually try to present some information about how things have been in the garden here in the hope that others might be tempted to do something similar.  That's not seeking comparisons between Westcott and other sites (all will be different, due not least to effort and local habitat), but looking at how each one's results compare to previous years at that same site.  With dissections for 2022 completed earlier than usual (many thanks, Peter), I have an excellent idea already as to what kind of year it has been for moths at Westcott so here are a few statistics to compare with previous years:

Number of nights the lights were run (1st Jan to 30th Nov):  310, of which 121 were with a single twin-30w actinic and the remainder with two traps (37 nights using two twin-30w traps and the remainder with one 125w MV & one twin-30w actinic).  That amount of effort is broadly similar to the previous four years, although running two actinics in the garden is not something I've tried before. 

Number of species caught:  742, comprising 382 micros and 360 macros.  That is the highest annual species count ever for the garden, exceeding last year's record total of 712 by a significant margin. 

Nights with 100+ species:  18, spread between 16th June and 1st August and all using both traps (125w MV and twin-30w actinic).  A further 13 nights came quite close with more than 90 species recorded and the results from one of those (19th July, 96 species) came from the actinic alone because the MV failed not long after it was switched on and contained zero moths when inspected at dawn.  The night with the highest species total was 11th July with 167, while 17th & 18th July shared second place with 154 each.  The year's results are certainly an improvement over both 2020 and 2021, being broadly similar to 2019 but still not as good as 2018 when there were 26 nights with 100+ species.

Best night for moth numbers:  2nd August when the total came to 782 individual moths (of 91 species).  The best night for species (11th July) had produced only 660 moths.  The second highest moth count occurred on 21st July (706 moths of 138 species) and that was the only other date on which the total surpassed 700.  Those figures are not at all exceptional here and, for example, have a way to go to catch up with the regular 1,000+ nightly totals achieved during 2019 using the same two traps.  

Highest overall counts for a single species:  Common Footman (1,575), Large Yellow Underwing (1,439) & Lunar Underwing (1,248) for macros and Acentria ephemerella (2,195), Agriphila tristella (547) & Patania ruralis (491) for micros.  In all, seven specific species passed the 1,000 barrier, the other three being Flame Shoulder, Setaceous Hebrew Character & Common Wainscot.  Heart & Dart (674) showed an improvement over its dismal performance in 2021 but still has a way to go to get back to its normal position amongst the highest counts.  Small Square-spot (512) was also working its way back up towards another peak after a trough of just 17 individuals in 2019.  It seems to undergo regular cycles like this lasting seven or eight years.

New for the site in 2022:  Seven macro and 16 micro species which, incredibly, is almost identical to the results for 2020 & 2021 and takes the garden lepidoptera count to 1,096 (606 micro, 458 macro & 32 butterfly species).  The new macros comprised Raspberry Clearwing & Sallow Clearwing both to pheromone lures during the daytime, while the overnight traps brought in Yellow Horned (common locally, long awaited), Jersey Mocha (migrant), Rest Harrow (migrant), Wormwood (widespread but seldom comes to light) & L-album Wainscot (spreading).  Of the micros, two were added as leaf-mines (Eriocrania sangii on birch, Phyllonorycter tenerella on hornbeam) and two as by-catch to pheromone lures (Triaxomasia caprimulgella to LUN, Pammene giganteana to MOL) while the remainder came to light:  Tineola bisselliella, Caloptilia populetorum, Caloptilia alchimiella, Povolnya leucapennella, Acrocercops brongniardella, Scrobipalpa ocellatella, Coleophora discordella, Elachista rufocinerea, Merrifieldia baliodactylus, Cnephasia pasiuana, Epinotia trigonella & Pempelia palumbella.   

Total number of moths caught in the garden (1st Jan to 30th Nov):  38,069 which is a marked improvement over 2021 (29,330 for the year) but nowhere near the total achieved in 2019 (54,400).

So to summarize, moth diversity at Westcott was above normal levels while moth abundance showed a recovery from the low of 2021 but was still significantly down on what was achieved in 2019.

2022 will be remembered as a particularly good year for migrants although Ancylosis oblitella was probably the only interesting one here not already mentioned.  Most of those seen at Westcott were the more common species - there were just more of them than usual.  They included Vestal, Four-spotted Footman, Small Marbled, Bordered Straw, Scarce Bordered Straw, Small Mottled Willow, Delicate & Pearly Underwing as well as Hummingbird Hawk-moth, Silver Y & Dark Sword-grass which are annual visitors.     

Dave Wilton Westcott, Bucks