A Review of Lepidoptera in the British Isles during 1971

TRANSACTIONS A REVIEW OF LEPIDOPTERA I N THE BRITISH ISLES DÜRING 1971 BARON DE W O R M S

AFTER on the whole another very mild winter, spring got under way early in March bringing out several kinds of hibernating butterflies and moths rather earlier than usual. One of the more localised species which was unusually numerous at this time of the year in its restricted haunts was the Dotted Chestnut (Dasycampa rubiginea Schiff.) mainly during March and early April when there was also a remarkable abundance of the Yellow-horned (Achlya flavicornis Linn.). T h e sallow bloom was only out the first days in April which saw a particularly congenial period over the Easter holiday. Insects in the Lake District were especially plentiful at this time, in particular the Orange Underwing (Archiearis parthenias Linn.), the Twin-spot Quaker (Orthosia munda Schiff.), and the Early Grey (Xylocampa areola Esp.). Except for a few days in its last week, the whole of April was mainly very warm and sunny as was the first half of May. Many spring butterflies were out to some extent in spate, notably the Orange-tip (Anthocharis cardamines Linn.) and the Holly Blue (Celastrina argiolus Linn.). These two species were soon followed by the two small Fritillaries with the Small Pearl-bordered (Clossiana selene Schiff.) more numerous than for many years. But virtually hardly any of the regulär immigrants had arrived by the end of May, notably the Red Admirals and Painted Ladies.

In contrast to 1970 the first half of June of this year was well below average in temperature with much rain and wind. In fact it was mostly a very bleak and blank month for lepidoptera in general providing one of the rare Hawks, a single example of the Bedstraw (Celerio galii Rott.) on the Kent coast, but there was no evidence of any large-scale invasion of this fine insect. T h e month of July, however, made up for any deficiencies in June, since it turned out a remarkable spell of warmth and sunshine with the thermometers soaring to near 90°F in the shade on the 1 Ith. T h e summer butterflies seemed to benefit substantially from this period of almost tropical heat. It was especially gratifying to learn that the Large Blue (Maculinea arion Linn.) was in very good numbers in one of its lesser-known haunts in the south-west.

Another of our finer butterflies which seems to be making a comeback after a great many lean years is the High-Brown Fritillary (Argynnis adippe Schiff.). It reappeared in the New Forest, in particular, in fair plenty during July. In this famous area too the Silver-washed Fritillary (Argynnis paphia Linn.) was also Aying in larger quantity than usual. Another delightful insect which

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appears to be reviving in southern England is the Wood White (Leptidea sinapis Linn.) which produced quite a prolific second brood in August. Later in July the Chalk-hill Blue (Lysandra coridon Poda) was once more possibly in more than average numbers on the Surrey downs and the same can be said of the Adonis Blue (Lysandra bellargus Rott.) which was in exceptional profusion during the late summer in this area. August also saw the presence of one or two of the few rarities recorded for 1971.

Most notable was a specimen of the Dusky Hooktip (Drepana curvatula Borkh.) taken in a light-trap in north Norfolk, a most unexpected region to find this Continental species which has had only one previous record, from east Kent in 1960. It is a question of possibly yet another new coloniser likethe Large Frosted Orange (Gortyna borelii ?\mti = lunata Freyer) which was found to be breeding in numbers in the stems of Hogsfennel (Peucedanum officinale) in a remote part of the east coast during September.

This handsome moth is very probably yet another newcomer from the other side of the Channel due to the gradual warming up of some of the more northerly parts of Europe. During the late summer a few moths were especially plentiful. Notable among these was the Autumnal Rustic (Amathes glareosa Esp.) which swarmed especially in the Orkney Islands where a large proportion is always the melanic form edda which constitutes nearly 50% of the population there. At this time of the year too there were records of only a very few Convolvulus Hawks (Herse convolvuli Linn.), at least one of which found its way as far as the Orkneys.

There was also a small immigration of the little Vestal (Rhodometra sacraria Linn.) in the south during the early autumn. During one of the sunniest months of October on record very few Red Admirals (Pyrameis atalanta Linn.) appeared with a very occasional Painted Lady (Pyrameis cardui Linn.) together with quite a spate of Small Tortoiseshells (Aglais urticae Linn.) and a very good showing of the Comma (Polygonia c-album Linn.). Quite late in the year several White-Speck Wainscots (Leucania unipuncta Haworth) were recorded in parts of the country including the east coast where this well-known migrant species seldom penetrates.

The year 1971 was one of the few in recent times which had been so little distinguished either for any spectacular abundance of butterflies or moths or for any large influx of some of the more regulär or rarer migrants.

Baron de Worms, M.A., F.R.E.S., Three Oaks, Shores Road, Woking, Surrey.