2094       Agrotis crassa (Hübner, 1803) GREAT DART

A central and southern European species, resident in the south-east coastal regions of Jersey and Guernsey, and a scarce immigrant to the coasts of south and south-east England, the larva leading a subterranean existence feeding on the roots of grasses and plants, and recorded as a serious pest in vineyards. In Dorset, singletons have been seen on twenty-three occasions, all but four from Portland and all at light traps. Many of the dates coincided with immigration from abroad, but a transient colony may have become established for several years following the hot summer of 2003 on Portland: West Bexington, on 9 August 2004 (R Eden), Wyke Regis, on 7 August 2003, 13 August 2004 (D Foot), Portland, on 19 August 1987, on 6 August 1989 (F Clafton), on 2 August 1991, 30 July 1992, 5 August 1994, 27 July 1995, 7 August 1995, 5 August 1996, 11 August 1997, 12 and 17 August 2004, 1, 6, 14 and 16 August 2005, 24 August 2007, 16 August 2008 (M Cade), on 4 August 1994 (B Skinner), Southwell, on 8 August 2005 (via PBO), Swanage, on 30 July 2008 (R Cox).

2098       Axylia putris (Linnaeus, 1761) FLAME

A lowland species found throughout Britain, the larva feeding nocturnally on herbaceous plants. In Dorset, this invariable moth is ubiquitous and frequent to common, but rarely abundant. The national norm is for a single brood in June and July, and this is the case in Dorset, but many individuals noted in May and again in September, suggest an occasional additional bivoltine cycle. Unusually high numbers of adults were trapped on 28 June, 3 August and 10 August 1994; see graphic of numbers trapped across the county during this year. It seems likely that many of the moths seen on the peak dates were primary immigrants from central or western France. The following late examples may have been out of season emergences, but are more likely to have been immigrants transported on south to south-easterly airflows established on both occasions from southern Europe: West Bexington, 10 October 2006 (R Eden), Higher Hyde, 13 October 2006 (Dr P Sterling), Gaunts Common, on 2 November 1983 (Miss M Brooks).

2099       Actebia praecox (Linnaeus, 1758) PORTLAND     Notable/Nb

A very local species confined to sandy coasts in Britain, the larva feeding nocturnally on creeping willow (Salix repens) and on sand dune plants, and then hiding in a burrow in the sand by day. In Europe, the moth also inhabits gravelly river shingle. The name of the moth was coined following the capture of a specimen by the Duchess of Portland, indeed, historically, a colony existed on Chesil Beach and it is possible that the original moth hailed from this colony. Until recently, it has been headquartered on the dune slacks at Studland, although the last record from this locality was eighteen years ago. Creeping willow is locally frequent on bogs in the Poole Basin, but rare on dune slacks. Given the increasing human pressures on sand dune habitat and their flora plus the scarcity of creeping willow on Studland, it is understandable that the species has declined to the point of extinction in recent years on this SSSI. Singletons trapped elsewhere in the Poole Basin are likely to have been wanderers from Studland. The Hengistbury Head record from the early part of the last century hints at a colony on the dune systems located there at that time, but regular trapping in recent years has failed to yield a single specimen. Before 1950, an extensive sand dune system over a kilometer in length, existed between Friar’s Cliff and Mudeford, and untrampled sand dunes were established at Hengistbury Head. Conservation measures for this species are equivalent to those discussed for Sand Dart, and this species should also be explicitly referenced in the National Trust management plans for the Studland and Brownsea Island SSSIs. Non-Studland records follow: Portland, (Duchess of Portland), Chesil Beach, in 1843 (E Curtis, C Dale), Ballard Down (Reverend E Bankes), Sandbanks, (W Parkinson-Curtis et al), Furzebrook, at MV light on 3 July 1976, 5 July 1976 (Professor N Webb), Arne Wood, at MV light on 25 August 1970, 17 August 1971, 24 August 1971, 25 August 1971, 25 June 1987 (B Pickess), Brownsea Island, at MV light on 20 August 1965, 12 July and two on 6 August 1967, 6 and 9 August 1985 (A Bromby), Hengistbury Head, at light on 24 August 1929 (R Demuth).

The record below is the only example seen west of Purbeck for more than a century, and is likely to have been an immigrant. There is an outside chance that the individual may have originated from Studland but its absence there since 1991 plus a hot east to south-easterly airflow up to the time of capture, suggests a primary immigrant. The species is found over much of northern Europe and Scandinavia: Portland, at MV on 1 August 1995 (M Cade).

2102       Ochropleura plecta (Linnaeus, 1761) FLAME SHOULDER

A species that occurs widely across Britain, the larva feeding nocturnally on herbaceous plants. In Dorset, the moth is ubiquitous and common, increasing to abundant in open areas. The peak of the second brood is roughly 70% more numerous than the first, on average. Unusually high numbers of adults were trapped in 1994 between 30 July and 10 August, as shown in the graphic of numbers trapped across the county during 1994. Immigration from western Europe is likely, as the peak coincided with warm south to south-easterly airflows. Another large influx occurred during early August 2003: Durlston, 89 at MV light on 7 August 2003 (J McGill), with a similar weather pattern established to that in 1994. The Flame Shoulder is very similar to Radford’s Flame Shoulder_2102.1 and any ‘Flame Shoulders’ caught in October and November should be examined carefully in case they turn out to be the migrant species.

2102.1   Ochropleura leucogaster (Freyer, 1831) RADFORD'S FLAME SHOULDER

A southern European species first recorded in Sussex in 1983 with a handful of records along the south coast subsequently, the larva leading feeding on trefoils (Lotus spp.) and other herbacious plants. The moth prefers open, dry, warm situations, and is double-brooded on the continent, the first brood on the wing in April and May, the second in the autumn. The author found the species to be common in the vicinity of dried-out salt-marsh habitat at Beziers in France on the Mediterranean coast. In Dorset, the moth has been seen at light traps on seven occasions: Walditch, on 29 November 2000 (M Parsons), West Bexington, on 18 October 2001, 22 October 2008 (R Eden), Portland, on 11 November 2001, 11 November 2004 (M Cade), Puddletown, on 31 October 2002 (H Wood Homer), Durlston, on 17 October 1990 (D Brown). Diagnostics include: a longer wing than Flame Shoulder₂₁₀₂; a smaller orbicular stigmata; white hindwings lacking reddish scales; ‘flame’ (along costal edge) extending well beyond reniform stigmata.

2104       Standfussiana lucernea (Linnaeus, 1758) NORTHERN RUSTIC

A local montaine and rocky coast species restricted to northern and western districts of Britain plus a few localities along the south coast of England, the larva feeding on various grasses and herbaceous plants including harebell (Campanula rotundifolia), saxifrage (Saxifraga spp.) and stonecrop (Sedum spp.). In Dorset, the moth is confined to the Purbeck coast and Portland where it is rarely recorded. It has a protracted flight period, and may be seen at any time between mid-June and early-September. Its habit of dashing wildly about on sunny days in the middle of the afternoon seems not to have been observed in the county. It is fond of visiting valerian flowers at night.

2105       Rhyacia simulans (Hufnagel, 1766) DOTTED RUSTIC

A local species on calcareous soils with a discontinuous distribution, resident in central southern England, north-west England and north Wales, in the Scottish Highlands and in the Hebrides and Orkney, the larva foodplant is unknown.

In Dorset, the moth is likely to have the status of immigrant and transitory or aestivating resident, although the most recent record is from 1992. “A consideration of these records leaves the impression on me of an immigrant that occasionally succeeds in getting a brood through, but has no real foothold.” (W Parkinson Curtis ms). The moth has most often been seen on Portland: “On valerian growing on tips from the first quarry south of Church Ope Cove; moths restricted to valerian growing among huge boulders 5'-6' across. The moth emerges in early July, hides amongst rocks and crawls up to valerian at late dusk; if disturbed it falls to the ground showing no signs of flying. After aestivation, it appears in September and then flies.” (R Demuth).

The species occurs across central Europe, as does a second and very similar species, Rhyacia lucipeta. This latter species is also known to migrate and although there are no British records to date, care should be taken when identifying any Dotted Rustics encountered.        

2107       Noctua pronuba (Linnaeus, 1758) LARGE YELLOW UNDERWING

One of the most abundant moth species in Britain (the adult female is capable of producing up to two thousand eggs), the larva feeding nocturnally on various herbaceous plants and grasses. In Dorset, the moth is ubiquitous and common to abundant, especially in open areas. Occasionally huge aggregations of the moth occur, and light traps at such times become inundated often at the expense of the more interesting species. The following light trap records are of single night catches in excess of eight hundred moths. All are on or very close to the coast and most coincided with notable immigrations from abroad, where it is a known migrant: West Bexington, 1000 on 16 July 1996, 870 on 27 July 2001 (R Eden), St Albans Head, 1500 on 7 August 1992 (P Davey), Arne Wood, 1150 on 14 July 1978 (B Pickess), Durlston, 2000 on 29 July 1992, 1000 on 2 September 1998 (P Davey), 5000 on 26 June 2003 (P Davey, S Nash), 1240 on 7 August 2003 (J McGill), Highcliffe, 3000 on 13 July 1982 (E Wild).

Although the adult is stated to fly between late June and early September, the flight period stretches from late-May to mid-November in Dorset, a period of nearly six months. Male adults are said to live for up to three months, whereas females live up to four months. It is likely that the moth aestivates during the summer as it does abroad, and this behaviour may explain the dip in numbers between late July and the early September, see phenology chart. The following individuals were recorded at light traps on very early dates and with airflows from southern Europe on each occasion, these are likely to have been primary immigrants: West Bexington, on 25 April 1996, 30 March 2003 (R Eden), Motcombe, 3 May 2006 (P Butter), Wool, on 2 May 2003 (D Cooper), Gaunts Common, two on 29 April 1994 (P Davey), Durlston, 1 May 2005 (P Davey, G Hopkins), Poole, 1 May 2007 (V Giavarini), St Ives, on 4 May 1989 (Dr J Clarke), Hengistbury Head, on 4 May 2003 (M Jeffes).

There is much variation in the coloration of the forewings of both sexes, and this is clearly evident when the moth is at rest. However, variation in the colour of the hindwings is rarely noted, as the hindwings remain tucked away out of sight until the moth becomes airborne. The only variety noted in the county is ab. postnigra trapped at Durlston on 26 June 2003 (P Davey), where the usual orange-yellow was suffused with black, making the hindwings appear caramel-coloured.

2108       Noctua orbona (Hufnagel, 1766) LUNAR YELLOW UNDERWING      Notable/Nb

A local and declining species with a scattered distribution across Britain, the larva feeding nocturnally on cock’s-foot (Dactylus glomerata), common couch (Elytrigia repens) and reed canary grass (Phalaris arundinacea). The adult is thought to aestivate between late-July and mid-August. In Dorset, the moth used to be frequent very locally within two markedly different bioptypes, heathland and chalky grassland, but has declined to the point of extinction over the past thirty years. The last record was from the far north-east of the county: Scrubbity Barrows, at MV light on 15 July 1997 (P Davey). “This distribution is curious. It is to be noted that whilst not by any means uncommon in the heath and pine area of the south-east of the county, it is well represented in the cretaceous of Purbeck and abundant in the cretaceous of the north-east of the county.” (W Parkinson Curtis ms). There is no evidence of immigration to Dorset. There may have been some confusion on the naming of this species in the past as Tutt persisted in identifying orbona (Hufn.) as equalling comes (Hubn.); whether this fact impacts the validity of some of older records is unknown. Continued monitoring for this species in Chase Woods is recommended.

2109       Noctua comes Hübner, 1813 LESSER YELLOW UNDERWING

Found throughout Britain in most habitats, the larva feeding nocturnally on most plant species. In Dorset, the moth is ubiquitous and frequent, increasing to common in open areas and amongst scrub. The flight period between July and September holds true, although singletons have been trapped as early as mid-May and as late as early November. Aestivation may account for the dip in numbers in the middle of August, see phenology chart. The following light trap records are of single night catches in excess of fifty moths, all noted from coastal localities. Unusually high numbers of Large Yellow Underwing₂₁₀₇ were noted on the same dates: West Bexington, 53 on 6 August 1994 (R Eden), St Albans Head, 150 on 7 August 1992 (P Davey), Durlston, 100 on 29 July 1992, 65 on 26 July 2006 (P Davey).

2110       Noctua fimbriata (Schreber, 1759) BROAD-BORDERED YELLOW UNDERWING

A species of extensive deciduous woodland and parkland throughout Britain, the larva feeding nocturnally on various herbaceous plants and also on the buds of tree species during the spring. The adult is thought to aestivate during August. In Dorset, the moth is frequent and occasionally common in deciduous woodland. The dip in August is likely to reflect diminished activity due to aestivation. High nightly totals have included forty on 29 July 1992 at Durlston; this date is also mentioned in the Large Yellow Underwing₂₁₀₇ and Lesser Yellow Underwing₂₁₀₉ accounts. The extremely similar Noctua tirrenica occurs in southern Europe, and although there are no British records to date, it may be worth retaining the occasional yellow ‘Broad-bordered Yellow Underwing’ at times of immigration for closer inspection. Both species are deemed to exhibit immigrant behaviour abroad.

2111       Noctua janthe (Borkhausen, 1792) LESSER BROAD-BORDERED YELLOW UNDERWING

A species with a wide distribution in Britain, the larva feeding on various herbaceous plants and shrubs. In Dorset, the moth is common rising to abundant in deciduous woodland. Unusually high numbers of adults were trapped between 30 July and 10 August 1994, as shown in the first graphic of numbers trapped across the county during the summer of that year. These peaks contrast markedly with the numbers for an average year, 1998, shown in the second graphic. The simultaneous immigration of Flame₂₀₉₈ and Flame Shoulder₂₁₀₂ moths has been discussed in each of their accounts. A more recent immigration event involving this species, was noted on the coast: Durlston, 270 on 5 August and 350 on 7 August 2003 (J McGill).

2111.1   Noctua janthina [Denis & Schiffemüller 1775] LANGMAID’S YELLOW UNDERWING

Added to the British list in 2001 following a capture on the Hampshire coast in that year, a widespread species in central and eastern Europe, more local further west, including western France, the larva feeding on various herbaceous plants and shrubs. In Dorset, four moths were seen for the first time in 2003, and thereafter thirty-one during 2004, four in 2006, one in 2007 and four in 2008. It might be possible that this new addition to the British fauna becomes established in grassland habitat in the county, but there is as yet, no firm evidence to support this. Diagnostics include a much reduced region of yellow on the hindwing, being completely surrounded by a broad black border.

2112       Noctua interjecta Hübner, 1803 LEAST YELLOW UNDERWING

A local species restricted to southern Britain, the larva feeding on herbaceous plants and grasses. In Dorset, the moth is at low density, and ranges from frequent on unimproved grassland on all soils to absent in woodland. Unusually high numbers of adults were trapped at West Bexington on 1 August 1995, as shown in the graphic of all Least Yellow Underwing moths trapped across the county during that year. It is likely that many of the moths recorded on this date at West Bexington were immigrants from north-east France, or from further east in northern Europe (see account of Portland₂₀₉₉ plus weather map for 1 August 1995).