ROTHAMSTED INSECT SURVEY

TRAP OF THE MONTH

Dear All,

Welcome to October’s Trap of the Month, the nights have started to draw in, the moths take on the hues of fallen leaves and we begin to navigate the national jigsaw that is the tiered lockdown system. Hopefully Mike will be able to visit sites that need attention, but we ask you to please bear with us as we make our way through the second wave.

We have good news to report from Rothamsted. Dan Blumgart is now our former PhD student after passing his viva last month. Congratulations Dan! His thesis on moth declines has some very interesting findings that we will be featuring in Trap of the Month in due course. Dan is staying with the Survey on a short-term basis to help with the production of the next State of Britain’s Larger Moths before potentially departing to Borneo to study long-term insect monitoring in the tropics.

Last month the Big Butterfly Count results came out and it did not make for happy reading. The lowest counts in the 11 years the project has been running. There are a few caveats in the report, including the suggestion that, due to an unusually warm spring and early summer the three-week window of the BBC was too late to capture the peak of butterfly emergence. It will be curious to see how the moths have fared this year We’ve had some indication from Identifiers that the numbers of moths appear to be down on previous years, but we’ll have to wait until the data are crunched to have a real picture.

Link for the results of the Big Butterfly Count: https://butterfly-conservation.org/news-and-blog/big- butterfly-count-2020-the-results

Trap of the Month – Rutland Water (579)

For this month’s newsletter we return to the UK to England’s smallest county Rutland, home of the largest reservoir (by surface area) in England, Rutland Water (Fig. 1).

More information on Rutland Water: https://www.lrwt.org.uk/rutland-water

Fig. 1: Southern section of the current Light-trap Network, the location of Rutland Water is indicated by a red dot

We give thanks to the trap’s operator Joe Davis who is the Senior Reserve Officer for Rutland Water Nature Reserve for the following information describing the surrounding habitat of the light-trap at Rutland.

The trap is set in grassland near the village of Egleton about 15m away from one of 8 lagoons at Rutland Water Nature Reserve. The trap is situated (Fig. 2) on the shallow western end of Rutland Water Reservoir.

This is an internationally important nature reserve and is managed by the Leicestershire & Rutland Wildlife Trust in partnership with Anglian Water. It provides one of the most important wildfowl sanctuaries in the UK, with in excess of 25,000 ducks, geese and swans in the winter months. It is also a wonderful mix of habitats including wildflower meadows, woodland, reed bed, open water and scrub (Fig. 3).

Fig. 2: Rutland Water light-trap

Fig. 3: Wider satellite view of Rutland Water, the trap is situated at the western end of the southern branch of the reservoir.

Like most sites we have covered in Trap of the Month, the annual total count (Fig 4) is showing a decline, with a distinct multi-annual cycle evident. The average annual count is 2,334, notably the first ten years the yearly average was 2,788 and the second ten years of operation recorded an annual average of 1,881. The first year, 2000, produced the highest count with 4,412 and last year 2019 produced the lowest count of 1,138. Overall, 314 species were recorded, the list is attached.

Fig. 4: Annual total count at Rutland Water

Ten species have topped the yearly annual counts over the duration of trapping, these are shown in Table 1:

Year Common Name Binomial Name Total 2000 Small Square-spot Diarsia rubi 318 2001 Lunar Underwing Omphaloscelis lunosa 173 2002 White Ermine Spilosoma lubricipeda 148 2003 White Ermine Spilosoma lubricipeda 189 2003 Silver-ground Carpet Xanthorhoe montanata 189 2004 Common Footman Eilema lurideola 259 2005 Straw Dot Rivula sericealis 212 2006 Straw Dot Rivula sericealis 465 2007 Straw Dot Rivula sericealis 256 2008 Straw Dot Rivula sericealis 290 2009 Straw Dot Rivula sericealis 515 2010 Straw Dot Rivula sericealis 290 2011 Flounced Rustic Luperina testacea 246 2012 Hebrew Character Orthosia gothica 149 2013 Straw Dot Rivula sericealis 199 2014 Straw Dot Rivula sericealis 169 2015 Straw Dot Rivula sericealis 142 2016 The Snout Hypena proboscidalis 71 2017 Straw Dot Rivula sericealis 133 2018 Square-spot Rustic Xestia xanthographa 194 2019 Lunar Underwing Omphaloscelis lunosa 118 Table 1: The most common species caught for each year

The majority headed the annual counts once or twice except the Straw Dot, which was the most common species in ten years: 2005 to 2010, 2013 to 2015 and 2017.

Looking more closely at the Straw Dot (Fig. 5). The first three years had low single figures for this moth before jumping to three figures in 2004 and in 2009 it recorded its highest count with 515. It has slowly declined and for 2019, only 29 were recorded, this rise and fall nicely mirrors the national trend since 2000 (Fig.6).

Fig. 5: Straw Dot, image by Nick Greatorex-Davies (UKMoths)

Fig. 6: National trend graph for Straw Dot

With the following species accounts we highlight moths that specialise in marshy localities, damp woodland and similar habitats.

The first is Small Dotted Buff (Photedes minima) (Fig. 7), this moth showed fluctuating counts over the first half of operation. In the last four years, counts have been low and 2019 produced just one solitary individual. The national trend shows a similar decline (Fig. 8).

Fig. 7: Small Dotted Buff, image by Ian Kimber (UKMoths)

Fig. 8: National trend graph for Small Dotted Buff The second moth is the Dingy Footman (Eilema griseola) (Fig. 9), at Rutland Water it occurred in low single figures in the first 5 years of operation, before increasing to double figures in 2006. There were three years that recorded over 100 moths, those were in 2010, 2013 and 2018 with 122, 127 and 105 respectively. Again, compared with the national trend graph (Fig. 10), the species follows a similar pattern at Rutland Water to the national picture.

Fig. 9: Dingy Footman, image by David Painter (UKMoths)

Fig. 10: National trend graph for Dingy Footman One of thirteen “wainscots” recorded at Rutland, Webb’s Wainscot (Globia sparganii) (Fig. 12), has never occurred in high numbers at Rutland Water. In fact, it was not until 2006 that the first record was logged. It has appeared regularly from 2012 and in 2016, 2018 and 2019, numbers reached double figures of 22, 24 and 26 respectively.

Fig. 12: Webb’s Wainscot, image by Steve Barrett (UKMoths)

We finish with a collection of the other wainscot moths (Figs. 13 to 18) that have been recorded on site at Rutland Water.

Fig. 13: Common Wainscot (Mythimna pallens) and Smoky Wainscot (Mythimna impure), images by Ian Kimber (UKMoths)

Fig. 14: Southern Wainscot (Mythimna straminea) and Shoulder-striped Wainscot (Leucania comma), images by Ian Kimber (UKMoths)

Fig. 15: Large Wainscot (Rhizedra lutosa) and Small Wainscot (Denticucullus pygmina), images by Nick Greatorex-Davies and Chris Johnson (UKMoths)

Fig. 16: Bulrush Wainscot (Nonagria typhae) and Brown-veined Wainscot (Archanara dissolute), image by Steve Barrett and Ian Kimber (UKMoths)

Fig. 17: Silky Wainscot (Chilodes maritima) and Fen Wainscot (Arenostola phragmitidis), images by Paul Harris (UKMoths)

Fig. 18: Mere Wainscot (Photedes fluxa) and Twin-spotted Wainscot (Lenisa geminipuncta), image by Ian Kimber and Paul Kitchener (UKMoths)

Mike’s Maintenance Matters

Hi everyone,

Hope you are all doing ok. Just the normal reminder for those with dose pumps, look out for soggy samples. If you increased the dose over the summer, you'll need to bring it down. I'm finding a single dusk dose of 3 seconds is a good average. I'm getting around sites gradually, upgrading with pumps and photocells etc, dodging local lockdowns. Do shout if you need anything or have a problem.

Thank you for all your help, stay safe, Cheers Mike.

ROTHAMSTED INSECT SURVEY: a BBSRC National Capability

Trap of the Month©Rothamsted Research 2017 The Rothamsted Insect Survey is a BBSRC supported National Capability with additional support from BBRO, AHDB and others. This report is for information only and may not be reproduced.

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