70.237 (1917) Early Thorn Selenia dentaria (Fabricius, 1775)

Resident. Common.
Flight period

Somerville (1858) during a visit to the Moffat area in August of that year had found the larvae on birch. Lennon (1863) had found it at his work place, the Crichton Institution, Dumfries. Gordon (1919) had found it common, flying along hedgerows at dusk around Corsemalzie (VC74) during mid-April to mid-May. The summer brood is rare but had occurred during early to mid-August on a few occasions. Earliest date was 29th April 1911.
Russell (1944) while staying at Gatehouse of Fleet during 1942-43 had found it locally. Sir Arthur Duncan (1909-84) during his lifetime had found it at Closeburn, Tynron and Castlehill, Dumfries. Pelham-Clinton recorded the only record during the 1950s at Glenluce (VC74). There were a further seven records from 1960-73, three from VC74, the rest in VC73.
In 1974 the Rothamsted station was running at Gatehouse of Fleet, from 1975 at Caerlaverock WWT and from 1976 at the other five sites producing sometimes over a hundred records per year, (175 in 1976). Then, from 1992 to 2010 over 400 records were amassed, quite a lot from the regular home trapping sites, but also further afield in widely scattered localities, proving this to be our commonest thorn with twice as many records as any other.
Life cycle
Two generations. Overwinters as a pupa. Larvae are present mid-May to Late June, again August to early October.
Larval foodplants
Alder, Blackthorn, Bog-myrtle, Downy Birch, Hawthorn, Hazel, Honeysuckle, Sallows and Silver Birch.
The unique resting position of holding its wings over its back pressed together will separate it from all other thorns.
Gardens, hedgerows, scrub and woodland areas.
© Keith Naylor, Mersehead RSPB, 18 August 2006
© Stephen Riddell, Maxwelton Mains, 20 July 2013

Local distribution map

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Distribution map displays records from the National Biodiversity Network (See terms and conditions).

The following datasets are included:

  • Butterfly Conservation - Macro-moth provisional distribution for the British Isles (excluding the Republic of Ireland) from the National Moth Recording Scheme
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