A review of Lepidoptera in Britain during 1976

A REVIEW OF LEPIDOPTERA IN BRITAIN DÜRING 1976 B A R O N DE W O R M S

FOR the third year in succession there was a congenial Start to the New Year, though the season was not nearly so precocious as at the opening of 1975. However, most of January and February saw very mild conditions with little sign of winter and most of the early species of lepidoptera well up to their normal time of appearance. There was also only one short-lived cold snap during March which ended on a really warm note. April too saw plenty of sunshine with the Easter holiday during the middle week of the month proving one of the finest in recent years. A feature was the most luxuriant blooming of the sloe in all parts of southern England. During this period the Early Grey moth (Xylocampa areola Esp.) and the Pine Beauty (Panolis flammea Schiff.) had been in unusual plenty, the latter among pine plantations. T h e early White butterflies, notably the Small White (Pieris rapae Linn.) as well as the Orange-tip (Anthocharis cardamines Linn.) were well out by the end of April. May opened with a veritable heat wave which brought out a flood of species, notably the Wood White (Leptosia sinapis Linn.) and the Holly Blue (Celastrina argiolus Linn.). Among the moths the Scarce Prominent (Odontosia carmelita Esp.) was exceptionally numerous in some parts of the south. About the middle of May the little Duke of Burgundy (Hamearis lucina Linn.) was also abundant in several localities as was the Small Blue (Cupido minimus Fuessl.) on the South downs and it appeared too even in late June in the northernmost areas of the Highlands. After a period of scarcity the Broad-bordered Bee Hawk (Hemaris fuciformis Linn.) reappeared in some quantity in some of its old haunts often seen Aying over bügle with the Pearl-bordered Fritillary (Clossiana euphrosyne Linn.) which also had a good showing in most of its known localities.

June turned out to be yet another warm and very productive month ending with one of the hottest periods recorded during the present Century with the shade temperature reaching 95°F for several days in succession. This excessive warmth brought out insects in the greatest abundance and often many weeks ahead of their normal time.

Several of the more spectacular woodland species of butterflies appeared in exceptional profusion at this period. Most notable among these was the Silver-washed Fritillary (Argynnis paphia Linn.) which could be seen in hundreds in many parts of southern England with its dark form of the female f. valezina occurring in many localities where it had not been seen before. Many grand aberrations of this fine insect were recorded including at least one halved gynandromorph. T h e White Admiral (Limenitis Camilla Linn.) was on the wing by the middle of June with quite

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a number of its melanic form f. nigrina being seen with as many as four in one wood in a single day. The Purple Emperor (Apatura iris Linn.) followed suit being noted as early as June 23rd. Both these species too were much more plentiful than usual and they were still Aying at the end of July. It was at the turn of the year that a remarkable discovery was made in South Wales by Dr. Neil Horton who in late July, 1972, took a specimen of the small noctuid since named the Silurian (Eriopygodes imbecilla Fab.) which had never been noted before in the British Isles. He tried in vain to find its headquarters in subsequent years as he was sure it was a native. In late June, 1976, he went to another mountain area and was delighted to find it quite commonly, Aying both by day and Coming to light as well. It seems very extraordinary that this small moth should have escaped notice for so long. It seems to be essentially an alpine species in Europe.

T h e great heat wave continued unabated at the start of the second half of this amazing season with quite tropical temperatures and a most spectacular superabundance of nearly all the lepidoptera. Even in the Highlands the first days of July were scorching. The Large Heath (Coenonympha tullia MĂźll.) was Aying in remarkable numbers with a very good showing of both the Mountain Ringlet (Erebia epiphron Knock.) and the tiny Scotch Brown Argus (Aricia artaxerxes Fab.). In the Lake District the fine High-brown Fritillary (Argynnis adippe Linn.) was also in exceptional plenty since it has become much less numerous in the South of late. The second brood of the Wood White (Leptosia sinapis Linn.) was already out by mid-July with lots of Purple Hairstreaks (Thecla quercus Linn.) and fresh Brimstones (Gonepteryx rhamni Linn.). The Small Skipper ( Thymelicus sylvestris Poda.) was swarming everywhere over the southern counties. The summer brood of the Peacock (Inachis io Linn.) was already on the wing by mid-July. Most species of moths which normally appear right at the end of the month or in early August were out too by this period, especially the Common Tiger (Arctia caja Linn.) and the Gold-tail (Eupr actis similis Linn.).

Some of the Blues, notably the Chalkhill (Lysandra coridon Poda), were even more precocious. This insect was on the wing on the Surrey downs at the end of June and continued in the greatest profusion in many localities well into August. A similar story can be told of several other butterfiies, in particular the Marbled White (Melanargia galatea Linn.), the Gatekeeper (Maniola tithonus Linn.) and the Silver-spotted Skipper (Hesperia comma Linn.). Several moths, as was to be expected with the intense heat, began producing unusual second emergences. Among these was the Poplar Lutestring (Tethea or Schiff.) in early August which saw a continuation of the general heat wave with the thermometer often well above 80°F in the shade. In the middle

235 of the month there was a fine second emergence of the Adonis Blue (Lysandra bellargus Rott.) in most of its known haunts.

Not much had been heard of any migrant insects as yet in 1976 and at one time it was thought it was going to be another lean year for them like so many of its predecessors. However, a huge wave of migrants burst upon the south and east coasts of England about the third week in August. Cornwall and in particular the Lizard Peninsula received one of the main streams at this time. One of the most notable visitors from abroad in this region was the Convolvulus Hawk-moth (Herse convolvuli Linn.) which must have come over in phenomenal numbers, since at least a hundred were recorded in a few days there. This fine moth which was noted almost all over the British Isles and well into Scotland, was also accompanied by several other choice species. The Striped Hawk-moth (Celerio livornica Esp.) and the Bedstraw Hawk-moth (Celerio gallii Rott.) were recorded together on the same night in south Cornwall. With them was a huge influx of the Delicate Wainscot (Leucania vitellina Schiff.) together with a good many of the White-speck Wainscot (Leucania unipuncta Haworth) and the White-point Wainscot (Leucania albipuncta Schiff.) which had not appeared in numbers for some years. The dark Swordgrass (Agrotis ypsilon Hufn.) and the Silver-Y (Plusia gamma Linn.) also arrived in prodigious quantity.

By day there were a great many Red Admirals (Nymphalis atalanta Linn.) with quite a number of Painted Ladies (Pyrameis cardui Linn.) mainly at buddleia bloom which also attracted several Humming-bird Hawk-moths (Macroglossa stellatarum Linn.) but a notable absentee was the Clouded Yellow (Colias croceus Fourcroy) of which very few were seen even in this extremity of the British Isles where it is usually quite prevalent. A few of the Cosmopolitan (Leucania loreyi Dup.) reappeared. While this invasion was in progress in the west, another one was starting on the east coast where during the third week in August the first Camberwell Beauties (Nymphalis antiopa Linn.) were reported.

This great immigration of this grand butterfly steadily built up during the first part of September tili it had been recorded from almost every English County as well as several from Scotland, Wales and even from Eire and the Shetland Isles. At least 280 individuals have been noted. This is by far the largest number since 1872, the last time the Camberwell Beauty visited our islands in a somewhat similar fashion. It is eagerly hoped some will reappear during 1977 after hibernation. There is evidence that they came across the North Sea direct from Scandinavia.

Many were seen Aying across Denmark. A few were recorded from Suffolk as mentioned elsewhere. Several species of immigrant moths also arrived on our eastern seaboard at this period.

Most notable of these was our largest andfinestnoctuid the huge A REVIEW OF LEPIDOPTERA IN BRITAIN

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Blue Underwing or Clifden Nonpareil (Catocala fraxini Linn.) which was reported in several localities in the Eastern Counties Coming to light-traps in early September. It was also taken in the Wye Valley and in northern England and Scotland. After the War it was resident in East Kent for about ten years. Another big noctuid moth, the Great Brocade (Eurois occulta Linn.) appeared infrequently in south and eastern England at this period, yet another migrant since it is normally resident in the Highlands. Düring this late summer period the newly discovered Leech's Sandhill Rustic (Luperina nickerlii leechi Goater) occurred in good numbers in its restricted haunts in the southwest, while its near relative Guenee's Sandhill Rustic (L. nickerlii gueneei) was found to be reasonably common on the North Wales coast where it had only been taken very sporadically previously, since its disappearance from St. Anne's in Lancashire early this Century. Other migrant species were seen at this remarkable period in less numbers but were nonetheless of special interest.

Among the butterflies were several Queen of Spain Fritillaries (Issoria lathonia Linn.) and the Long-tailed Blue (Lampides boeticus Linn.) seen on the south coast and in the Midlands, while a most amazing capture was made in mid-Wales of a Viceroy (Limenitis archippus Linn.), a Nymphaline species inhabiting North America, which mimics the Monarch (Danaus plexippus Linn.). How it arrived here must be the subject of much speculation, as it is the first record for the British Isles. Unexpected captures of moths mainly on the east coast provided specimens of the Golden-rod Brindle (Lithomoia solidaginis Hübn.), the Gold Spangle (Plusia bractea Schiff.) and the Scarce Silver-Y (Plusia interrogationis Linn.), all three denizens of our northerly regions like the Great Brocade. Migrant geometers also figured at this time. These included Blair's Mocha (Cosymbia puppillaria Hübn.), the Vestal (Rhodometra sacraria Linn.) and the Gern (Nycterosea obstipata Fab.), as well as the rare Pyralid the Yellow Underwing Pearl (Uresiphitapolygonalis Schiff.), mainly on the Lizard. Following the flood of the Convolvulus Hawk-moth came quite a wave of the famous Death's Head (Acherontia atropos Linn.), mainly in early October. Some of them no doubt had emerged from larvae bred up in this country. Another rarity, reported from Suffolk at Southwold was a specimen of the Scarce Chocolate-tip (Clostera anachoreta Schiff.), seen at least once before in the county.

With the great summer heat second broods were most likely.

One of these was that of the White Admiral seen Aying in September in Surrey. But what was even more remarkable was the appearance of freshly emerged Peacocks (Inachis io Linn.) in October, never known before. Full-fed larvae of this butterfly were found in late August and the imagines bred out. Even the Purple Emperor was bred out in captivity in September. T h e

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autumn moths proved for the most part very numerous, especially the Dotted Chestnut (Dasycampa rubiginea Schiff.) and Blair's Pinion (Lithophane leautieri Mab.) which reappeared in the London area. Finally two rarities were recorded in the autumn.

One was the Small Pyrale Antigastra catalaunalis Dup., a species with its main home in Africa and the Near East which has very seldom been taken in Britain. This insect was taken in North Kent towards the end of September. The other was a record in mid-October in Sussex of the handsome Flame Brocade (Trigonophora flammea Esp.) of which very few examples have been noted in the last fifty years, though it used to occur regularly mainly in Sussex during the last Century, always in the autumn.

Yet another rarity was a Spurge Hawk-moth (Celerio euphorbiae Linn.) found sitting on a warehouse door on October 13th in the East End of London.

The year 1976 can be Said to have well earned for itself the title of an 'annus mirabilis' which will long be remembered not only for the abundance of our lepidoptera but also as one of the hottest and most prolonged summers on record.

Baron de Worms, M.A., Ph.D., F.L.S., F.R.E.S., M.B.O.U., Three Oaks, Shore's Road, Horsell, Woking, Surrey.