Atropos migrant insect review – end August/early September 2011

After a rather dull and cool first three weeks of August, the last few days of the month and early September saw southerly winds, with a resulting increase in immigrant moth activity.

Odonata highlights included records of a male Lesser Emperor Anax parthenope from Windmill Farm, Cornwall, on 14 August and of a pair at the Long Pits, Dungeness, Kent, until at least 17 August. Six Red-veined Darter Sympetrum fonscolombii were also noted at the Cornish site on 14 August.

Records of the recent colonist Willow Emerald Damselfly Lestes viridis were made in Norfolk and Essex. The species appears to be spreading out from the centre of its population in Suffolk. The other recent arrival - Small Red-eyed Damselfly Erythromma viridulum was widely reported.

A Clouded Yellow Colius croceus well inland at Highworth, Wiltshire, on 7 August was noteworthy in what has been a particularly lean year for the species. A slight increase in records of Painted Lady Vanessa cardui was evident, particularly from Dorset, Kent and Suffolk.

August was most notable for the occurrences of some very rare immigrant moths with records in Dorset of Rosy Underwing Catocala electa at West Bexington (P. Sterling) and Pine-tree Lappet Dendrolimus pini at Portland (B. Skinner) on the night of 22 August. The following night a further record of electa came from Guernsey, Channel Islands (P. Costen). Other megas included Pale-shouldered Cloud Actinotia hyperici on 11 August at Saltwood, Kent (P. Howe); Crimson Speckled Utethesia pulchella by day at Formby, Lancashire, on 25 August (R. Hill) and a Beautiful Marbled Eublemma purpurina at Dungeness, Kent, on 29 August (D. Walker) – the latter surprisingly the first area record.

Rare but annual in the British Isles nowadays were singles of Dusky Hook-tip Drepana curvatula reported from Sandwich on 9 August and Pegwell on 13 August (both Kent); Oak Processionary from Alderney, Channel Islands on 20 August. Quite an influx of Ni Moth Trichoplusia ni also occurred with records from Dorset, Kent, Essex and inland to Worcestershire.

There was exciting news regarding the other Eublemma - Small Marbled Eublemma parva. Good numbers of larvae have been located on Fleabane Pulicaria dysenterica along the south coast with reports from Cornwall, Devon, Dorset and the Isle of Wight. For many lepidopterists this has been their first opportunity to rear the species, with strikingly marked, darker adults, emerging over the past week or so.

The so called ‘regular immigrant moths’ were in short supply with many moth-trappers failing to catch anything better than Dark Sword-grass Agrotis ipsilon, Silver Y Autographa gamma, Rush Veneer Nomophila noctuella or Rusty-dot Pearl Udea ferrugalis or Diamond-back Moth Plutella xylostella.

Reports of Gem Orthonama obstipata came from the Channel Islands, Cornwall and Dorset; Vestal Rhodometra sacraria from Dorset, Kent, Essex and inland to Herefordshire; Delicate Mythimna vitellina from Cornwall; Cosmopolitan Mythimna loreyi from Sandwich, Kent; Scarce Bordered Straw Helicoverpa armigera from Dorset and West Sussex; Small Mottled Willow Spodoptera exigua from the Channel Islands, Isles of Scilly, Dorset and Lincolnshire with Convolvulus Hawk-moth Agrius convolvuli from Isles of Scilly, Dorset, Kent,Borders and Shetland.

It has been a good year for immigrant Dark Crimson Underwing Catocala sponsa following the three trapped on the night of 2 August in Kent, Essex and Suffolk. Further records came from Dymchurch, Kent and from Bonchurch, Isle of Wight.

Rare immigrant pyrales included Mung Moth Maruca vitrata at Littlehampton, West Sussex, (T. Freed) on the night of 2 September – there are only a handful of British records of this attractive species. Palpita vitrealis were noted in Cornwall and Dorset and Conobathra tumidana also in Dorset.

Atropos would like to thank you for your contributions to the Flight Arrivals webpage. September can be a very exciting month for rare immigrants; keep a look out for Death’s Head Hawk-moth Acherontia atropos, Clifden Nonpareil Catocala fraxini (one of which has already been reported from Hampshire this autumn) and the chance of rarer plusias – perhaps a Dewick’s Plusia MacDunnoughia confusa or a Golden Twin-spot Chrysodeixis chalcites.