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Suffolk. Natural History, Vol. 33
NOTES AND COMMENTS ON SOME SUFFOLK MOTHS IN 1996 M. R. HALL Many of the reports on moths seen in 1996 have emphasised the number and variety of the migrant species recorded during the months of June, July and August and indeed these at least equalled and possibly exceeded those noted in 1995. However, when many of the resident species are considered the picture emerging is less optimistic and it is the status of. these regularly occurring, usually common, species that better indicates the overall health of our Lepidopteran fauna. The general decline of several of the autumn flying species that was mentioned in 1995 continued in 1996. Both the beaded chestnut, Agrochola lychnidis, and the brown-spot pinion, Agrochola litura, were again sparsely recorded whilst their compatriot the lunar underwing, Omphaloscelis lunosa was somewhat more in evidence with all the recorders who note species on a regulär basis, year on year. The November moths, Epirrita spp., were also at a low ebb as were the canary-shouldered thorn, Ennomos alniaria; dusky thorn, Ennomos fuscantaria, and large thorn, Ennomos autumnaria. The scarce umber, Agriopis aurantiaria; September thorn, Ennomos erosaria, and flounced chestnut, Agrochola helvola, would seem to be very elusive and have been recorded hardly anywhere in the county for several years and the pale eggar, Trichiura crataegi, has apparently been non-existent. Unfortunately it is not only the autumn species that are seemingly declining at the moment. Once common species like the drinker, Philudoria potatoria; lunar marbled brown, Drymonia ruficornis; garden tiger, Arctia caja\ white ermine, Spilosoma lubricipeda\ feathered gothic, Tholera decimalis, and straw dot, Rivula sericealis, were all reported as being in decline and even species that are seen regularly, if not frequently and in good numbers, caused comment by their non appearance. In particular the läppet, Gastropacha quercifolia; white-pinion spotted, Lomographa bimaculata, and streamer, Anticlea derivata, caused such comment as did the much lower than usual numbers of the angle shades, Phlogophora meticulosa. Several recorders also remarked on the comparatively small numbers of the silver Y, Autograph gamma, that came to light in their traps. This is an interesting Observation in light of the huge numbers of this migrant species that could be seen at flowers by both day and night and obviously the catch in mercury vapour moth traps in no way reflected the true occurrence of this species. One can only speculate on the relevance of these observations to other species. Fortunately there are several species that occasioned equal comment for their increasing prevalence. Some like the common wainscot, Mythimna pallens, at Monks Eleigh (AW) and the large nutmeg, Apamea anceps, at Nowton (RE) were also prolific in 1995 (although population changes were out of phase with Monks Eleligh) whilst others, particularly the spruce carpet, Thera britannica; pine hawk-moth, Hyloicus pinastri: Blair's shoulder-knot, Lithophane leautieri ssp. hesperica, and Vine's rustic, Hoplodrina ambigua, show a continuing increase associated with expanding ränge. Vine's rustic was long regarded as an immigrant species which, at the best, became only a temporary resident, but since the 1940s it has become well established in southern England and has
Trans. Suffolk Nat. Soc. 33 (1997)
NOTES ON SOME SUFFOLK MOTHS
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since progressively extended its ränge across the south east of the country. This extension of ränge has been helped by large influxes of migrants in hot years. 1996 saw a similar very large invasion of the common noctuid the large yellow underwing, Noctua pronuba, and presumably some other common species, that are both migrant and resident, as well. Increases were also reported in the numbers of single-dotted wave, Idaea dimidiatcr, Shoulder stripe, Anticlea badiata; scorched wing, Plagodis dolabraria, and the cream-spot tiger, Arctia villica ssp. britannica. There does appear to be a fairly regulär cycle of annual increase followed by a decline in the population for some species, and not necessarily a similar cycle of abundance for all species, and these species may have reached their population peak. The dotted rustic, Rhyacia simulans, was noted at Nowton (RE) and has not been seen in the county since the 1980s. This is a species that appears on the wing in late June and early July and then aestivates to reappear in late August and September and was first noticed in East Anglia in the late 1970s. Another species which also appeared at Nowton (RE) after a period of absence is the dusky-lemon sallow, Xanthia gilvago. This is a widely but thinly distributed species and with larvae feeding on wych-elm, Ulmus glabra, (and more rarely on other species of elm) closely reflects the status of the foodplant in the county. In the last three years the least carpet, Idaea vulpinaria ssp. atrosignaria, seems to have become established in East Anglia with more than two dozen being reported from Landguard Observatory, Felixstowe (NO), eight at Berners Road, Felixstowe (JN), four at Sicklesmere (SD) and singletons at Scole (MH) and Wroxham (NB) in Norfolk. Felixstowe also saw the first baisam carpet, Xanthorhoe birivata, recorded in Suffolk (NO - det. G.M. Haggett) on the 7th August and a Single red sword-grass, Xylena vetusta, (NO) in September. Whilst this latter species is regarded as a resident in much of Great Britain it is said to be rather local and generally scarce in the eastern counties and it is more likely that this individual was a migrant. On the other hand the baisam carpet is a species of lightly wooded water meadows (where the larval foodplants are to be found) and although not uncommon in Middlesex, Surrey and North Hampshire is found sparsely in East Norfolk and Cambridgeshire and could be another species that is moving into Suffolk. This species is double brooded with individuals of the spring brood somewhat similar to the common carpet, Epirrhoe alternata, and those of the summer brood not unlike the dark-barred twin-spot carpet, Xanthorhoe ferrugata, and thus any 'aberrations' of these two species should be carefully examined or referred to an expert for identification. In 1995 a Single marbled green, Cryphia muralis, was recorded at Landguard (NO) but as neither specimen nor photograph was available the record could not be confirmed. Another singleton came to light at the same place in August 1996 and this time the specimen was retained to confirm the record. This is a mainly maritime species with larvae feeding on yellow lichens growing on walls and apparently the only previous Suffolk record is from Needham Market in the second half of the last Century. Larvae of another maritime species the crescent striped, Apamea oblonga, were found on Orford Ness (GH). This is characteristically a species of salt marshes and banks by the sea with larvae feeding on the roots and stem-bases of saltmarsh grass, Puccinella spp.
Trans. Suffolk Nal. Soc. 33 (1997)
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Suffolk Natural History, Vol. 33
The larval webs of the small eggar, Eriogaster lanestris, were noticed at two sites in 1996. Webs were found on elm at Horham (SG) and on blackthorn at Yoxford (JW). This nationally scarce species is on the wing in February and March and thus rarely recorded at light but the larval webs are really obvious along hedgerows in late June and July. Several comparatively common moths are under-recorded as they are exclusively day flying so records of the orange underwing, Archiearis parthenias, from Bradfield Woods (SD) in April and the Mother Shipton, Callistege mi, from the King's Forest (AW) in June are particularly pleasing. These species, together with half a dozen other common day-flying species, are easy to see and relatively easy to identify and are thus well worth adding to 'target' species for non-specialist naturalists on day-time field trips. The clearwings are another group of day-flying moths but with their mimicry of various hymenopterans are not so easy to identify. One of the commonest, and most frequently reported, is the hĂśrnet moth, Sesia apiformis, whose larvae feed for two, or possibly three, years in the trunks and upper roots of black poplar, Populus nigra, and occasionally other poplars. This species was again recorded from Nowton (RE) and also from Stowupland (JW) but it is certainly much more widespread than indicated by current records. There were two records of the ruddy carpet, Catarhoe rubidata, - one from Barrow (AP) and the other from Monks Eleigh (AW). Although this moth is widespread in the southern half of England and Wales it is local and has never been common anywhere despite having generalised habitat requirements. Another species that has been equally elusive is the orange footman, Eilema sororcula, although this species has a more specialised habitat need and is usually associated with mature oak woodland with the larvae feeding on lichens associated with the oaks (and also beech). The singleton recorded in 1996 on the 30th May came to light at Hollesley Common (AW) and its presence helps in confirming the record from Woodbridge reported last year. The Breckland speciality the grey carpet, Lithostege griseata, was recorded from Elveden (SD) and also some little way from its usual haunts at Barrow (AP). The pimpinel pug, Eupithecia pimpinellata, was also recorded at Barrow (AP). This species is locally widespread in southern and eastern England on embankments and roadside verges where its occurrence is determined by the distribution of its larval foodplant, burnet-saxifrage, Pimpinella saxifraga. The larvae feed from late August to early October in the ripening seed capsules and are thus very much at the mercy of Over zealous verge trimming. It is always intriguing to see records of species well away from their preferred specialist habitat. The flame wainscot, Senta flammea, which is a local species of coastal and inland reed-beds was reported from a wooded garden site at Weston (NM) although it is also regarded as a probable immigrant which could account for this sighting. The dog's tooth was seen in the Waveney Valley at Mettingham (MB) and although it is regarded as primarily a saltmarsh and coastal species in East Anglia. it is never really numerous which is borne out by just four being observed at Landguard (NO). This Felixstowe observatory (NO) also reported two specimens of the large ranunculus, Polymixis Ă&#x;avicincta, and with just one other record from Sicklesmere (SD) this supposedly 'not uncommon' moth of sea cliffs, gardens and waste places, with larvae feeding on a variety of wild and cultivated plants, has been surprisingly
Trans. Suffollc Nat. Soc. 33 (1997)
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elusive in Suffolk in recent years. The water ermine, Spilosoma urticae, which had evaded recorders in recent years until reported from Minsmere in 1994 was found again this year, at Darsham on a 'moth night' organised by the Suffolk Moth Group. It would appear this species is on an upward curve in its population cycle although it will always be a scarce moth. Migrant species of moths have been reported from across the county with the day flying humming-bird hawk-moth, Macroglossum stellatarum, attraeting most attention (RE, JG, SG, CH, GHs, JM, NM, NO, AP. ZR, RS, AW, JW). Other migrants reported were: the gern, Orthonama obstipata, (JN, NO); the convolvulus hawk-moth, Agnus convolvuli, (RE); the death's-head hawk-moth, Acherontia atropos, (EK, AM); dark sword grass, Agrotis ipsilon, (SD, RE, JN, NO, AP, AW); pearly underwing, Peridroma saucia, (SD, RE, NO, AP. AW); greät brÜcade, Eurois occulta, (SD, RE, SG); the white-point, Mythimna albipuncta, (RE, NO); golden-rod brindle, Lithomoia solidaginis, (RE); small mottled willow, Spodoptera exigua, (RE, NO); scarce bordered straw, Heliothis armigera, (NO, AW); bordered straw, Heliothis peltigera, (SD, RE, SG, JN, NO, AP, AW); silver barred, Deltote bankiana, (NO) and golden twin-spot, Chrysodeixis chalcites (see Clancy, 1997), see Plate 1. (NO - det. G. M. Haggett). I am sure there have been other sightings of migrant moths in 1996 but if the records have not been sent to either the county recorder, Arthur Watchman, or the Suffolk Biological Records Centre (or to me) where they can be verified if necessary, they cannot get included in this report. Do please send records for inclusion in future reports or outstanding records from earlier years to Arthur Watchman, 'Onchan', Back Lane, Monks Eleigh, Suffolk, 1P7 7BA, or the Suffolk Biological Records Centre, c/o The Museum, High Street, Ipswich, IP1 3QH. References Clancy, S.P., (1997). Variations within Golden Twin-spot Chrysodeixis cites Esper. Atropos, 3; 34.
chal-
Acknowledgements I thank all the recorders whose records and notes have helped to compile this report- N Bowman (NB), Maggie Brooks (MB), Stan Dumican (SD), Eddie Krutysza (EK), Jean Garrod (JG), Steve Goddard (SG), Gerry Haggett (GH), Colin Hawes (CH), Geoff Hayes (GHs), James Mann (JM), Audrey Morgan (AM) Norman Muddeman (NM), Jon Nicholls (JN), Nigel Odin and Mike Marsh (NO), Zoe Rimmer (ZR), Richard Stewart (RS). John Walshe (JW) and in particular Rafe Eley (RE), Adrian Parr (AP) and Arthur Watchman (AW) whose additional comments on numbers and fluctuations have been so helpful. M. R. Hall (MH) Hopefield, Scole, Diss, Norfolk IP21 4DY.
Trans. Suffolk Nat. Soc. 33 (1997)
Plate I: Aberrant specimen of Golden Twin-spot. Chrysodeixis migrant at Landguard Common. 1996 (p. 53).
chalciles
(Esper), a scarce