Entomologist’s Rec. J. Var. 122 (2010) 97 NOTES ON THE EARLY STAGES OF THE TRIANGLE HETEROGENEA ASELLA ([D. & S.], 1775) (LEP.: LIMACODIDAE) 1 R. J. H ECKFORd , 2 B. P. H ENWOOd & 3 S. d. BEAvAN 1 67 Newnham Road, Plympton, Plymouth, Devon PL7 4AW. 2 6 Lakeland, Abbotskerswell, Newton Abbot, Devon TQ12 5YF. 3 The Hayes, Zeal Monachorum, Devon EX17 6DF. Abstract Observations were made on the larva of Heterogenea asella ([d.& S.], 1775), in devon, England, including descriptions of the first instar, feeding signs and other larval evidence as well as cocoon formation and incidence of parasitism. Keywords: Lepidoptera, Limacodidae, Heterogenea asella , first instar, larval feeding, cocoon formation, parasitoids. Introduction Until 2004 Heterogenea asella had not been recorded in South devon (vice- county 3) since 1891, and was not known from North devon (vC 4) until 1999 (McCormick, 2001), where, so far, it has been found only in one locality. In 2004 and 2005 respectively, 16 and over 45 larvae were found in two areas about 5 km apart in South devon. Modern British publications suggest that the larva feeds on the upperside of leaves of oak ( Quercus spp.) and beech ( Fagus sylvatica ) high in the canopy. Barker, Fuller & Shreeves (2000) consider threats to the species and conclude that, other than large-scale clearance of trees on which it breeds, any threats are presently unknown due to poor knowledge of its ecology. Ellis (2000) states that it is not clear whether high forest or coppice/recent plantation is the preferred habitat. Our observations are that the larva does not always occur high in the canopy and, at least on oak, it feeds on the underside of the leaves. We found larvae in areas of mature deciduous trees. We describe and illustrate what seem to be previously unpublished characteristic feeding signs and larval evidence which may enable more records to be made, and provide an account of the first instar and cocoon formation. We also consider the incidence of parasitism, which may have a significant effect on populations. Distribution and certain historic accounts Porter (1997) gives the British distribution as Wiltshire, Hampshire, Sussex, Kent, Oxfordshire, Buckinghamshire and Lincolnshire, where it is local in a few mature woods. He omits Warwickshire, Worcestershire, Cornwall and devon, although records are indicated from these counties according to the distribution map provided for the species by Skinner (1985). Presumably the reason that Porter does not mention devon is because of the lack of records between 1891 (Basden- 98 Entomologist’s Rec. J. Var. 122 (2010) Smith, 1891) and the publication of his book in 1997. The species has also been found in two Essex woods (Waring, Townsend & Lewington, 2003). On this basis, H. asella has only been recorded from 12 counties in the British Isles, all in England. One of the main areas for the species is the New Forest, South Hampshire (vC 11). It may be significant that Goater (1974) gives a number of records from vC 11, but all, apparently, of adults. Several have been published in this journal over the years and, as far as we can trace, for the period from 1880 to date all are of adults, mainly at light, except the following larval records: at least two larvae, foodplant unstated, in the ‘New Forest’ in the autumn of 1880 (Jobson, 1881), several larvae, foodplant unstated, between 1884 and 1892 at Lyndhurst (Hewett, 1890; Hewett, 1893), a larva beaten from an unspecified source in the ‘New Forest’ in 1933 (Symes, 1961). Hewett (1890) records collecting various larvae at Lyndhurst between 15 and 16 September 1890, including one larva of this species on beech ‘after about one hour’s search’. Later he published a note (Hewett, 1893) which illustrates the avarice of certain collectors. If the species could not be found at Lyndhurst after 1892 then his note shows the potential reason, and so we quote it in full: ‘My experience of Limacodes asella may be to the point. When I began collecting these in 1884 I took twenty or so larvae in October at Lyndhurst. Two years after (I could get none in ’85) I searched for two hours and took one. I took it at almost the outset, so that my eye was not at fault. I bred that one and went down in 1886 and have been every year up to the present. I took five or six in 1888, I think Mr. H. A. Hill was with me, and took about the same number. Mine all died and so did his. Last year (1891) I took two and bred both. This year I went again, in rather a despairing mood and got several dozens, and Tate of Lyndhurst took two or three hundred I believe. I talked to him about them, and his experience exactly coincides with mine. Obviously then asella comes and goes. I hope the few members of the Exchange Club who have had larvae from me got them to pupate as well as mine have done – on the leaf or twigs. I have never taken the pupae in the wilds, nor has Tate. We have both searched carefully. Goodness knows where they go. The larvae must be searched for; no one can beat them in numbers. The picture in the Ray Society book is perfect, and from larvae of mine I believe .’ We assume that the Ray Society book referred to is volume 3 of The larvae of the British Butterflies and Moths (Buckler, 1888). Hewett lived in Winchester. For at least nine years he visited Lyndhurst and apparently collected every larva that he found, and we presume that, at least in 1892, Tate did the same. Apart from Entomologist’s Rec. J. Var. 122 (2010) 99 showing how many larvae he could find, Hewett’s note tells us nothing of the species’ ecology, not even the foodplant(s) apart from one found on beech in 1890, but it does make clear that the larvae needed to be searched for, rather than beaten. There is, however, one point of interest which is that, at least in 1884, he found larvae in October. We refer to this later. Lyle (1912) states that in 1911 larvae of this species ‘were almost entirely absent’ in the New Forest. In the same year Corbin comments (1912) that ‘we seldom hear of the large ‘takes’… which old Charles Turner … once took so commonly’ in the New Forest. This appears to be a reference to adults and not larvae. Whether this apparent reduction in the numbers of the species was the result of over-collecting the larvae or other causes, or both, is a matter of speculation. Earlier observations on finding the larva Tutt (1901), possibly based on Hewett (1893), comments that the larva must be searched for and cannot be beaten in numbers. Skinner (1985) states that the larvae of Limacodidae feed on the upper surface of leaves of trees and because of suction or adhesive silk are rarely dislodged by beating. Porter (1997) remarks that the larva can be obtained by beating, but only infrequently, which, in his view, probably indicates that it lives and feeds high in the canopy well out of reach although, as we found, this is not always the case. The photographed larva (Porter, 1997, plate 2: B) is recorded as being beaten from oak, full grown, in late September. This reference to a larva beaten from oak in September is the first published record that we can trace of a larva being found since Symes’ note of one in 1933. The only subsequent published record of the early stages of which we are aware is of a larva and cocoon being found on sweet chestnut, Castanea sativa and another larva and cocoon on small-leaved lime Tilia cordata , both at Stansted Forest, West Sussex on 12 September 2006 (Langmaid, 2007). None of these larval accounts mentions what seems to us to be characteristic larval feedings, at least on oak, that we describe later. Rediscovery in South Devon The species was first recorded in devon on 20 June 1890 by Mr F. J. Briggs (1890) who was beating for larvae during the afternoon and a pair of this species in copula fell into his umbrella; the plant or tree from which he beat these is not stated. The locality is given as ‘the Plym valley’ and Briggs’ address is given as Egg Buckland. He includes this record in some notes from Plymouth (Briggs, 1891), adding that ‘I am nearly certain that a third specimen which was secured was the same species, but not knowing the rarity of the species it was discarded, as it had been rubbed in capturing.’ This appears to be one of the first records of the species in the British Isles outside of the New Forest, Hampshire. The next devon record, and the last before 1999, is of a female from an unstated locality 100 Entomologist’s Rec. J. Var. 122 (2010) somewhere in ‘Plymouth’ in July 1891 by Mr H. W. Basden-Smith (Basden- Smith, 1891). Tutt (1899) summarises the then known localities of the species in the British Isles. He gives the following records from devon: ‘Plymouth (Basden-Smith), Plym valley (F. Briggs), Kimpton (Rudd)’. The Ordnance Survey Gazetteer of Great Britain published in 1987 gives all place names from the 1: 50,000 Landranger Map Series. It lists ‘Kimpton’ as a place name in Hampshire and also Hertfordshire, but not devon and so we believe that Tutt’s inclusion of this name was a mistake. We have not been able to trace anything about Rudd.