A REVIEW OF LEPIDOPTERA IN THE BRITISH ISLES DÜRING 1961 by
BARON DE W O R M S
THE winter of 1960-61 was one of the mildest for many years with virtually no snow in the South and very little severe frost. In addition the month of March was one of the sunniest and wärmest this Century with the result that the season was equally forward for most plants and the Lepidoptera in particular. The sallows were well in bloom by the second week of the month with the sloe blossom only a fortnight later. All the earlier Noctuid moths were well on the wing by this time, including the White-marked (Gypsitea leucographa, Hübn.) in Surrey. There was also quite a spate of the hibernated butterflies at this period, especially the Brimstone (Gonepteryx rhamni, L.). Thebeginning of April saw most of the Prominents already appearing in such a precocious spring, while the Muslin (Cycnia mendica, Clerk), was in remarkable numbers towards the end of April and early May. It was in this latter period that a very marked change came over this abnormally early season culminating in the last week of May with one of the most severe and destructive frosts at this time of year. This very cool spell put back all species almost behind their average time of appearance and many of the spring butterflies were much sparser than usual. This was especially so with two smaller Fritillaries, the two Pearl-bordered (Clossiana euphrosyne, L. and C. selene, Schiff.), which were very scarce in most of their usual haunts. June, however, opened with some much more congenial weather and the early part of this month saw the recording of an unusual number of the Marsh Moth (Hydrillula palustris, Hübn.), in its restricted haunts in the fen country. No other very outstanding captures were made during this period and most of the summer butterflies were generally regarded as being rather scarcer than usual, in particular the larger Fritillaries and the White Admiral (Limenitis Camilla, L.). T h e first day of July was one of the hottest in the south of England in recent years with temperatures well into the 90's and indeed a prelude to a much more exciting second half to the season. In the third week of that month there began an influx of immigrants which were markedly absent from the spring and early summer. T h e Bedstraw Hawk (Celerio galii, Rott.), was the first to be reported with several captures in the Home Counties, the Midlands and the Eastern Counties. This was followed by the appearance of the Large Footman (Lithosis quadra, L.), in apparently phenomenal numbers in the south-west, mainly in Cornwall, no doubt due partially to a large immigration. Not long afterwards in
LEPIDOPTERA I N THE BRITISH
early August the first of the attractive little geometer the Vestal (Rhodomotra sacraria, L.), was recorded. This amazing little migrant was reported during the subsequent two months all over the south of England where it had not been seen in such plenty since 1947. It even reached the Highlands where quite a thriving colony was discovered. It was also in early August that a most surprising addition was made to our moths. Two collectors on the Norfolk Broads obtained a series of the very local Dotted Footman (Pelosia muscerda, Hufn.), but noticed that one specimen seemed somewhat different in shape and markings. It was not, however, tili the early autumn that its true identity was established as Pelosia obtusa, Hübn., a species which is very elusive and difficult to obtain in thick marshland in Northern Europe. This insect may have been with us quite a long time and remained undetected owing to its habit of living in the thickest reedbeds. August also saw a singular lack of the common Yanessid butterflies, such as the Peacocks and Tortoiseshells and even the Red Admiral (Pyrameis atalanta, L.), was in poor numbers, while the Painted Lady (P. cardui, L.), and the Clouded Yellow (Colias croceus, Fourcroy), were only observed very sparingly in a few places in the southern counties. Towards the end of August the Adonis Blue (Lysandra bellargus, Rott.), appeared in considerable numbers in several localities where it had been very scarce for many years and it is gratifying to think that this butterfly may once more be on the up-grade. About this time too the Heath Rustic (Amathes agathina, Dup.), seldom a common moth, emerged in exceptional abundance over most heath and moorland all over the country, just when the ling was in füll bloom. It was during the last few days of August that some of the first records were made of the Crimson-speckled Footman (Utetheisa pulchella, L.), and during the next five weeks at least thirty were recorded in places from Cornwall to Kent, also several in Wales and two each from Ireland and the Scottish Lowlands. No such numbers of this most spectacular moth had been seen in the British Isles in any year this Century, in fact not since 1892. This insect is one of the most remarkable migrants and there must have been a very large scale invasion. For 20 years from 1932tol952 there was apparently only a single record. From a capture in Kent it was bred apparently for the first time from British stock. September was indeed a most remarkable month not only for fine weather, but also for many other rare migrants. Though the Delicate Wainscot (Leucania vitellina, Hübn.), was reasonably numerous in 1960, its numbers were nothing to be compared with those of 1961 when it was a really common insect mainly in the south-western area in the early autumn, but nevertheless there were a great many records all along the south coast and from quite a lot of places well inland, even from the London district.
LF.PIDOPTERA IN THE BRITISH ISLES
It had not been seen in such quaritity since 1938. Both the White-point and White-speck Wainscots (Leucania albipuncta, Fab. and L. unipuncta, Haworth), were also taken more common than most years along the southern seaboard, though the latter mainly frequents the south-western portion. There were other rarities captured during this amazing period, notably single specimens of the Milkweed (Danaus plexippus, L.), in South Cornwall, an Oleander Hawk (Daphnis nerii, L.), in the Midlands, a Purple Marbled (Eublemma ostrina, Hübn.), from Kent where a male Gypsy Moth (Lymantria dispar, L.), also appeared in a moth-trap, only the fourth to be recorded in 20 years for Britain. No less than five examples of Dumeril's Rustic (Luperina dumerili, Dup.), were reported in the South with two of the Slender Burnished Brass (Plasia aurifera, Hübn.). Another surprise arrival during this period was the rare little Pyrale Rambur's Chinamark (Diasemia ramburialis, Dup.), of which almost a record number were taken in the southern region of England. The early part of the autumn also saw the apparent spread in ränge of the Blacked-streaked Pug (Eupithecia phoeniceata, Ramb with captures in North Somerset and Dorset, while the Gern (Nycterosea obstipata, Fab.), was quite plentiful at this tim There were also several records of the Scarce Bordered Straw (Heliothis armigera, Hübn.), in the later months, but many of commoner migrant Hawks were markedly absent. The Convolvulus (Herse convolvuli, L.). was very scarce compared with 1960 and the Death's Head (Acherontia atropos, L.), was in very meagre numbers. Not a great deal was heard of the Silver-Y (Plusia gamma, L.), except for a phenomenal appearance one nig in East Kent in September when one collector found his garden smothered with them with an estimate of some 25,000 individuals. Few of the autumnal moths were exceptionally plentiful, except the Grev Pine Carpet (Thera obeliscata, Hübn.), which was in great abundance as a second brood. This account should not end without reference to another remarkable addition to our Lepidoptera, the Dusky Hook-tip (Drepana curvatula, Borkh.), of which a female was taken a light in East Kent in August, 1960, and a series bred from it in 1961, but its identity was not established tili late in that year which after a distinctly unspectacular Start turned out to be a most interesting and important season and one well to be remembered.