370         Sesia apiformis (Clerck, 1759)    HORNET     Notable/Nb

A local species confined to south-east England and East Anglia, the larva feeding for two or more years between the bark and the wood of mature poplar (Populus spp.), especially black poplar (Populus nigra) and aspen (Populus tremula) being located at the base of the trunk or in the roots.  The Hornet prefers mature poplars that grow in isolated clumps or in rows, and, like other clearwing species, a single tree can contain many individuals.  Small trees that host the species are often destroyed.  Newly emerged moths may be found close to the protruding pupa case.  The following record is unconfirmed, but the bright yellow ‘saddle-bag’ markings on the thorax of the moths were well described by J Lloyd the observer: Wareham, two moths paired at the base of a hybrid black-poplar (Populus nigra x deltoides) tree among a grove of poplars in July 2002.

371         Sesia bembeciformis (Hübner, 1806)    LUNAR HORNET

A predominantly south of England species, the larva feeding for two years low down within the trunks and in the upper roots of mature sallow species (Salix spp.).  The young larvae feed beneath the bark just below ground level, but later bore deeper into the host trunk creating a tunnel of up to 8mm diameter some 50mm above ground level.  The presence of a colony is occasionally revealed by damage to the trunks caused by woodpeckers searching for larvae and pupae.  The moth emerges between late June and late July and may be observed on a host trunk until noon, or later in overcast weather.  In Dorset, the moth is widespread and locally frequent, and larvae have been found within sallow trees growing in most situations. Two large swathes of sallow-birch woodland removed in heathland restoration work on Studland Heath during January in 2003 revealed twenty tunnelled stumps from a total of two hundred stumps.  The tunnelled stumps were located in distinct groups indicating the colonial nature of the species and illustrating perhaps the tendency to re-occupy a host tree year after year.  A further example of a favoured tree is evidenced by the observation of up to nine adults on a single sallow trunk in a garden at Preston during the second and third weeks of July 2002 by M Forster.

373         Synanthedon tipuliformis (Clerck, 1759)    CURRANT CLEARWING     Notable/Nb

A generally distributed species in England, the larva feeding and over-wintering once within strong stems of black currant (Ribes nigrum) and, less frequently of red currant (R. rubrum).  Eggs are laid close to the ends of shoots, or stems that have been pruned the previous winter.  The newly-hatched larva creates a tunnel by eating the heart of the stem in the late summer and into autumn.  During the spring, frass may be evident at the end of the host shoot, and, prior to pupation, a cap is constructed to seal the end of the tunnel. The moths emerge during June and may occasionally be observed at rest on currant leaves around midday; thereafter, females may be seen in the middle of the afternoon seeking out a suitable part of the bush to oviposit.  Localities in Dorset are few but the species is likely to be under-recorded, and colonies found in towns or nurseries are associated with well-established black currant bushes.  Pheromone lures employed by R Cook and D Humphrey at a nursery at Knighton attracted seventy males on 21 June 2001.

 374         Synanthedon vespiformis (Linnaeus, 1761)    YELLOW-LEGGED CLEARWING     Notable/Nb

A species restricted to central and southern England, the larva feeding and overwintering once within the cambium of oak (Quercus spp.) and, less frequently, birch (Betula spp.) trees.  Eggs are laid out of preference on stumps of oak trees that have been felled the previous year.  The resultant larva creates galleries by slowly feeding on the cambium layer through the autumn.  During the spring ‘sawdust’ frass may be visible on the stump surface.  Larvae of all sizes co-exist and the different development rates lead to a protracted emergence period stretching from May through to August. Occasionally adults may be seen flying in numbers around the oak stumps, especially in hot sunshine.  In Dorset, the moth is rarely looked for, and the records undoubtedly understate its frequency.  The species seems to prosper in oak woodland where coppicing and occasional felling of mature oak and birch is undertaken, but such practices have now all but died out, and colonies have proved hard to find in recent years. Conservation measures should include the maintenance of viable coppiced oak woodland in the county.

377         Synanthedon flaviventris (Staudinger, 1883)    SALLOW CLEARWING    Notable/Nb

A local south-eastern and central southern England species, the larva feeding for two years within slender sallow (Salix spp.) stems up to 12 mm in diameter.  For the first year there is little external evidence of the larva.  However, by the second winter, a gall up to 25mm long forms from the bulbous thickening of the sallow stem.  This internal activity often kills the stem above the gall.  Mortality of larvae at this time is high as blue tits and related species target the galls and ichneumon flies often emerge from collected galls.  It is a remarkable fact that moths are rarely seen or bred in odd years, so that galls tend only to be present in odd-even winters, eg. 2005-2006, 2007-2008 etc., and so the adult emerges between mid-June and mid-July in even years.  The species was first discovered in Britain in 1926 near Southampton; several years later it was found at Lytchett Matravers (per W Parkinson Curtis manuscript).  In Dorset, the moth forms scattered and small colonies in grey willow (Salix cinerea) bushes that grow on well drained sandy or gravel soils in the south-east of the county.  The following recent observation indicates the moth has also colonised a sallow-rich site at Alners Gorse in the Blackmore Vale, well away from its usual headquarters: ten sallow stems containing galls collected in February 2006 produced four longhorn beetles that emerged during April plus a single moth that emerged in late June (P Davey). Retention of good quantities of grey willow growing in open situations in known localities would assist with the conservation of this species in the county.

378         Synanthedon andrenaeformis (Laspeyres, 1801)    ORANGE-TAILED CLEARWING     Notable/Nb

A species limited to the calcareous soils of south-east and central southern England, the larva feeding for at least two years within the stems or branches (up to 25mm in diameter) of the wayfaring tree (Viburnum lantana), and, less frequently of guelder rose (Viburnum opulus).  In its final year of growth, the larva cuts a disc-shaped cap in the bark over the emergence hole; this structure is the only external evidence of the larva within.  The moth emerges through June and July.  In Dorset, many inland calcareous  localities have been found to harbour the moth, especially where old scrub containing mature wayfaring tree remains untouched on chalk downland.  This species tends to colonise single plants, leaving others nearby unaffected.  Retention of good quantities of wayfaring tree as part of the downland scrub mosaic would assist with the conservation of this species in the county.  Unfortunately such mosaics are seldom valued by conservation agencies, and continue to be reduced in extent or obliterated as they were during the reversion of downland to arable in the post-war years by farmers. 

379         Synanthedon myopaeformis (Borkhausen, 1789)    RED-BELTED CLEARWING       Notable/Nb

A species restricted to southern England, the larva overwintering beneath the bark of apple (Malus spp.) and less frequently pear (Pyrus communis), almond (Prunus amygdanus), peach (Prunus persica), rowan (Sorbus aucuparia) and hawthorn (Crataegus spp.).   The female tends to select wounded trees on which to oviposit, and the resulting young larvae burrow under the bark at the edge of the wounds.  Tenancy is occasionally evidenced by reddish frass hanging from bark crevices in the early spring; however, the micromoth Enarmonia formosana₁₂₁₆ also exudes frass from fruit-tree bark at this time.  The moth emerges before midday from mid-May until the end of June.  In Dorset, any decline in the number of cultivated, pesticide-free, apple trees and corresponding reduction in potential colonies is masked by the lack of fieldwork and thus records.  It is likely that colonies are present in old orchards, although this valuable habitat is disappearing, and in most towns where gardens and allotments containing well established apple trees. Gardeners should maintain their fruit trees without recourse to chemical sprays or applications to ensure the survival of extant Red-belted Clearwing colonies.

380         Synanthedon formicaeformis (Esper, 1783)    RED-TIPPED CLEARWING      Notable/Nb

A species found in England, the larva overwintering once beneath the bark of osier (Salix viminalis), goat willow (Salix caprea) and grey willow (Salix cinerea).  There is often little external evidence of occupation within the infected stem or branch.  Trunks or branches damaged by other insects may often be found to host the species and close inspection may reveal old emergence holes or empty pupa cases in the region of the wound.  A further occasional characteristic is a circular scar around the circumference of a willow stem and a thickening of the stem in the region immediately above the gall. The adult emerges during June and July.  In Dorset, the moth forms scattered and small colonies in willow bushes that grow beside rivers, ditches, ponds, fens, mire and marshes.  It is local but likely to be more widespread than the Sallow Clearwing₃₇₇ .  Retention of good quantities of sallow in known localities would assist with the conservation of this species across the county.

381         Synanthedon culiciformis (Linnaeus, 1758)    LARGE RED-BELTED CLEARWING     Notable/Nb

A species confined to England, the larva overwintering once and feeding in a tunnel between the wood and bark of birch (Betulae spp.) and, less frequently, of alder (Alnus spp.). Larval frass may occasionally spill out from bark crevices or the top-edge of birch stumps during the autumn. The moth is the first Clearwing on the wing, emerging from the beginning of May onwards before 1 pm; peak emergence tends to coincide with warmer spells of weather.  In Dorset, the moth is extremely local, with recent records from Bovington Heath, Chase Wood, Merritown Heath and Castle Hill Wood.  Several factors may be responsible for this.  The practice of coppicing all but died out by the 1960s.  Before this time, the rural community recycled the birch that provided much-needed firewood, rural products, and the space to graze livestock.  Since the 1960s, land management priorities have changed, large areas of birch and oak woodland have been replaced with conifers, the rural way of life has waned and the dependency on wood as a local resource with it.  As the moth appears not to be easily detected through the use of pheromone lures, the following Bere Wood records from the early part of the twentieth century provides a fascinating tip on detecting the adult in suitable situations: Bere Wood, fourteen adults found inside rhododendron flowers at midday on 4 June 1906 (W Parkinson Curtis), two adults sitting quietly inside rhododendron flowers at 2pm on 7 June 1906, four adults alighting on the top of rhododendron flowers at 2:30pm, 2:55pm, 2:55pm and 3:55pm, respectively on 8 June 1907, four adults in or on rhododendron flowers between 12:45pm and 1:45pm on 29 May 1908, eighteen adults in or on rhododendron flowers between 8:50am and 11:30am on 3 June 1908 (Reverend E Bankes), on a rhododendron leaf on 9 June 1906 (F Haynes). The moth requires coppiced birch in open woodland and on heaths; such a commodity is at a premium at the present time.  Conservation measures should include the maintenance of birch and alder trees through coppicing, among deciduous woodland. 

382         Bembecia ichneumoniformis [Denis & Schiffermüller 1775] SIX-BELTED CLEARWING     Notable/Nb

Recorded from most southern counties of England and Wales, the larva over-wintering once in the roots of common birds-foot trefoil (Lotus corniculatus) and kidney vetch (Anthyllis vulneraria), and in this state it is very difficult to detect.  The species tends to prefer chalk-pit edges, cliff ledges and disturbed calcareous ground where host plants abound.  Adults may be found relatively easily by sweeping or by carefully searching downland flora and grasses upon which the moth sits; the heads of salad burnet (Sanguisorba minor) are particularly favoured.  The moth emerges from the end of June until mid-August.  In Dorset, the moth has been recorded from many calcareous coastal locations and particularly from Portland where it is locally abundant, and is one of the less difficult Clearwing species to locate.  Dr P Sterling has observed freshly emerged adults sitting on horseshoe vetch (Hippocrepis comosa) on Portland, and it is likely that this is a host foodplant, at least on the island. R Cook and D Humphrey used a pheromone lure to attract seventy males at Easton on Portland in 2001.  Inland in recent years, it has been recorded from Bovington, Hod Hill, and West Hill on the Purbeck Ridge, but it is probably less widespread than it once was due to the loss of unimproved chalk grassland habitat.  No effort is required to conserve this species given that the foodplant is not threatened where colonies of the moth are found.