Saltholme moth report, 2023
It has been a cracking year recording moths at Saltholme. We've had our highest annual species count with 287 species recorded, 40 of which were new to Saltholme. The following is a roundup of the year’s efforts.
The first trap of the year was on the 28th January. It was the first January trap we’ve carried out on site, and it proved worthwhile; five moths, of five species were recorded, including Dotted Border and a couple of Agonopterix species, but the highlight was the first adult record for the county, of Acrolepia autumnitella, a very smart little moth that mines the leaves of Bittersweet. Larval mines were first recorded in VC66, in 2020, and at Saltholme the following year, and every year since in fact, on a plant next to the footpath, opposite the pollinator garden – ‘VC66’ is short for vice-county 66, the '66' referring to County Durham as defined in 1852 - the modern county has a slightly different boundary.
Acrolepia autumnitella
January produced another new species for the reserve; Coptotriche marginea. Two mines were found on Bramble at the Haverton scrub end of the site, again, right beside a footpath. There are only 26 records of this species on the county database, fewer than half of which are from this century, with most from the south-east of the county. We caught up with the species again in February, in a new location, and a new 10km square, near to the Wildlife Watchpoint hide.
March saw the good start to the year continue, with new site and 10km square records for both Early Grey and Beautiful Plume when they came to the light trap. Another highlight from March was an Orange Underwing seen in the Discovery Zone, our first record of this day-flying species. They fly high up at the tops of birch trees from midday on warm, still days, apparently with a habit of coming down to ground level and drinking from puddles later in the afternoon – a behaviour we never managed to observe!
Orange underwing – photo by Garry Hird
The second highlight from March, was trapping the first record for the county of Mompha sturnipennella, a species that has similarities with other Mompha species but particularly M.subbistrigella. The larvae feed over two generations on Rosebay Willowherb, the first cause a gall in the stem and the second feed in either the stem or a seedpod.
Mompha sturnipennella
April and May provided slightly disappointing light trap results with only six species across two dates in April, and 28 across two dates in May, the best of the lot was Small Elephant Hawkmoth on the 24th May, which is pretty much annual at Saltholme and probably breeds here with the amount of Lady’s Bedstraw we have, though we are yet to see the caterpillars. In the field there was a little more action with a couple of smart caterpillars. Helcystogramma rufescens is a very smart beast in caterpillar form, and it must be this that gives the moth one of its common names, ‘Common Zebra Moth,’ - its abdominal segments are covered in neat black and white diagonals, and it has a white dorsal stripe. After seeing our first last year, finding an individual in a curled grass leaf was a joy, also a joy, was finding the smartly marked Acrobasis advenella larva, on hawthorn at Dorman’s.
Acrobasis advenella larva
Perhaps most interestingly though, at the end of April, a Coleophora, or case-bearing moth, was found feeding on a Dog Rose along the pedestrian path. The larvae of Coleophora species construct a protective case out of silk and fragments of their foodplant, the adults are often difficult to identify but the cases can be distinctive, and when combined with the identity of the foodplant, individuals can often be identified to species. We struggled to find anything that fed on rose that matched the case, luckily Tim Barker, the county recorder for VC66 suggested C.lusciniaepennella and it looked a decent fit, although it is said to feed on Salix species and not rose.
Larval case on Dog Rose of Coleophora lusciniaepennella
We decided in the end to try and rear the individual so it could be identified by dissection. We are grateful to Dr Charles Fletcher for providing dissection services, and in the end proving Tim correct. We can think of two possibilities to explain the finding; either it has bred on rose which would be a new foodplant for the species, or, more likely, it had been dislodged from a nearby willow and finished its development on the rose, which in itself is fairly interesting. There is willow nearby and so that does seem most likely, but it must have been blown a few metres across a footpath and landed on the rose, roughly where it was found at about five foot off the ground. Either way, we will be checking the rose this Spring for sure - just in case!
May also brought some nice field records. Pyrausta purpuralis and Grapholita lunulana were both seen in a small area of quite interesting grassland to the north of the site – both are attractive little moths.
Common Purple and Gold Pyrausta purpuralis
Grapholita lunulana
A little time in late afternoon spent around the Meadow produced Elachista argentella, a grass feeding, all white (micro) moth, and several Grass Rivulet, the latter obviously doing well due to the abundant Yellow Rattle, whose seeds their larvae feed on. With milder winters becoming more frequent in the UK it may be that Grass Rivulet becomes a slightly scarcer moth. It is relatively common and widespread, but its foodplant, Yellow Rattle, does better after its seeds are subject to a period of 'freeze-thaw' over the winter known as vernalisation. This produces a higher germination rate and ultimately more flowers, and then seeds, which the caterpillars feed on.
In May we found mines of the nationally scarce Bucculatrix maritima on Sea Aster, from the relatively new and developing saltmarsh at Cowpen Marsh, south of Greatham Creek. It’s a good sign that species like this are turning up in this newly created habitat, presumably a population was already present in the small area of saltmarsh that remained on the creek. With one or two more projects leading to increased area of saltmarsh possibly in the pipeline on Teesside, there may be opportunities for more dots on the map in future.
Bucculatrix maritima mine on Sea Aster
Also at Cowpen Marsh, but just outside the sea wall, we found several caterpillars of the Triangle Plume moth. They feed in two generations on Coltsfoot, initially mining the leaves. The summer generation then feed externally, whereas the autumn generation enter the stem and overwinter in the rootstock, then climb up the inside of the stem in Spring to feed on the flower buds, flowers and then seeds. They then pupate in May amongst the white fluffy seed heads, also known as the pappus. Lastly, really good numbers of Dingy Footman caterpillars were seen on fenceposts at Dorman’s, 115 the highest recorded count.
In June, interest at the light trap picked up a little, and on the 8th a White-point turned up. A migrant species, they are usually recorded in the south and south-east of the country, so this was a really excellent record and a first in the county. Breeding occurs in the south-east in some years so it may possibly be one for the future.
White-point Mythimna albipuncta – photo by Matthew ‘Scabz’ Scarborough
On the 15th we had our first Spring record of Vine’s rustic after three autumn records and a peak count of four in 2022, but after this not a huge amount more of note.
July and August are typically some of the best months for moth abundance and diversity. On the 1st July, quite a highlight was our first adult Small Ranunculus, a species that has spread rapidly in recent times. Once resident in Southern England, it underwent a rapid decline and was thought to be extinct in the UK with no records after 1939. Then, in 1997, two individuals were recorded in Kent. It has spread rapidly since, reaching Stockton in the summer of 2020, and a caterpillar was found at Saltholme in Autumn 2021. We found caterpillars in 2023 as well, 26 in late August near to the Visitor Centre, feeding on Great Lettuce and a singleton on the Dragonfly Path, feeding on Prickly Lettuce.
Small ranunculus larva
On the 5th July, we spotted the wonderful Stathmopoda pedella, at rest on alder. It’s a curious little moth that holds its enlarged rear legs, with long spurs, perpendicular to its body and slightly raised. The larvae feed in the fruits of alder expelling orange frass. With a localised and generally more southerly distribution, it is a rare moth in the county, with only four previous records.
At first glance, Stathmopoda pedella, holding its rear legs aloft, doesn’t look much like a moth
On the 8th we came in to find 499 moths of 112 species in and around the trap, our record count. It was a ‘Moth Morning’ event, and such a catch was great, we loved having good numbers of visually impressive moths, like the 10 Garden Tigers, that can really capture people’s imaginations, but something else stole the show that day: Orthotelia sparganella. It is a locally distributed species of wet places, like Saltholme and rare in the county, this individual was the fourth, the last one was fifty years ago. Bur-reed seems to be the main foodplant and is quite scarce here, but Reed Sweet Grass is also listed and is very common, and is dominant in some of the ditches. It’ll be interesting to see if or when another record occurs. Some species seem to arrive, establish themselves and spread quickly, some seem to spread at a very slow pace and other species perhaps don’t find all they require and aren't seen again for some time. Other highlights from the catch included, Athrips mouffetella, a site first and a rare moth in the county, and Mugwort Plume which was only the ninth county record.
Orthotelia sparganella
On the 13th July, a Lunar Hornet Moth Sesia bembeciformis was found and rescued from the Holme Fleet. This is only the second clearwing moth recorded at Saltholme and we think you'll agree it is pretty fantastic. The individual found was a female, and must have come into some bother, probably whilst egg-laying, to be found in the fleet and actually had an egg glued to its wing. We initially thought she was dead but after a bit of time indoors it was clear she wasn't. We found a nearby willow and laid her down where she proceeded to lay more eggs. It seems it may be worth a little hunt around some of the willow on site next July as when adults emerge (they feed internally on the wood of willows,) they spend some time resting low down on the trunks of the foodplant.
Lunar Hornet Moth egg-laying on willow
On the 15th we caught The Wormwood again, having first caught this species in 2021. Last year larvae were found, but no adults came to light. This year, as well as the adult, larvae were found on its foodplant, Mugwort, around The Meadow in late August and early September.
White-line dart and Archer’s dart were both recorded in August. Neither are particularly common in the county and so were nice catches. Archer's dart is scarcer, and most of the county records are from the Teesmouth area, with some much older records, from the 19th Century, around the North-East of the county.
In September, trapping effort reduced somewhat, but another new plume moth for the site, Hemp-agrimony Plume (Adaina microdactyla), came to light on the 2nd, and was the 15th county record. The finding of a Satyr Pug larva was fortuitous on the 12th, feeding on ox-eye daisy growing by a security gate – this was a first for Saltholme and only the fifth record in the last 23 years in VC66.
In October we recorded a second Mompha sturnipennella, after somewhat appropriately, opening up one of the hatches of an insect hotel. Perhaps the most rewarding record was of the caterpillar of the Dowdy Plume moth (Stenoptilia zophodactylus) feeding on the flowers of Yellow-wort. The record is a first for the reserve, though the species is known from Teesmouth where Yellow-wort is a typical plant of the slag grassland, at Saltholme it also grows where clay subsoil is exposed. The caterpillar was reared and after six days, pupated on the foodplant, emerging two and a half weeks after that.
Dowdy plume on yellow-wort (from top, larva, pre-pupal larva, pupa, adult)
In November there are still moths that can be recorded and having had Hemp-agrimony plume to light a couple of months earlier, the team checked some of the Hemp-agrimony on site for feeding signs, and sure enough, after inspecting four or five stems, we thought we’d found the tell-tale signs of the hole in the stem underneath the flowerhead. One or two stems were removed and taken back to the office and the identification was confirmed on finding the quite distinctive larva inside.
Hemp-agrimony Plume larva in a Hemp-agrimony stem
The other record of note from November was a site first of the Firethorn Leafminer moth Phyllonorycter leucographella, whose mines were found near to Dorman’s hide on the 15th. This moth was first discovered in the UK in 1989, in Essex. The larvae mine the leaves of Firethorn, (Pyracantha) and it has spread really quite rapidly across the UK. The last record of 2023 was our second record of December moth on the 22nd November. The peak flight season in the county is late October and early November, possibly the reason we haven’t had many, though there are records as late as Christmas eve.
Over the year, 958 moth records were produced with a total of 3382 moths, larvae or mines being identified. This brings the total number of moth species recorded across the reserve to 480 and we'll be keeping our fingers crossed that in 2024, our 15th birthday year, that we reach the 500 mark! Massive thanks must go to all the team but also to Tim Barker the county recorder who provides huge amounts of support by helping with identification and verification of records and ultimately inputs everything to the county database adding value to it all.