The large tortoiseshell is an eye-catching medium to large butterfly with orange/red wings which have three costal (leading edge) black blotches and three large black spots in the middle of the forewing. Both wings have a blackish narrow terminal band which bears tiny blue spots in lunules of the hindwing. The underside of the wings is smoky brown with darker shades.

Behaviour

This butterfly is a migrant and found primarily in woodland, especially those containing willows, elm, poplar or rowan.

Males are solitary individuals, usually seen either in flight, or when basking on bare ground. In Britain, they have been reported nectaring at sallow catkins in spring, and bramble blossom and various herbaceous garden plants in summer. Females tend to bask on tree trunks, often in a head-downwards posture.

Eggs are laid in large batched around twigs in April. They hatch after about 3 weeks. The larvae are black, covered with sharp orange spikes and peppered with tiny white dots, giving them a greyish appearance. They live communally in conspicuous silk webs spun on the twigs of the food plants. In early June, the larvae descend from the tree tops to pupate, a stage which lasts about two weeks. The adults emerge and disperse quickly and hibernate in cool dark places until the following spring.

Size

• Wingspan: 6.8-7.2 cm (male); 7.2-7.5 cm (female)

Status

Believed to be extinct as a resident in Scotland and the British Isles; any sightings are considered to be migrants from the continent.

Distribution

The large tortoiseshell was once widespread and common in woodland in southern England and throughout Britain. However, it has suffered a dramatic decline with less than 150 records since 1951. The hope is that it will be able to re-colonise the British Isles, this hope being lifted by sporadic sightings (2000-2009 survey and later in 2019) in South Devon, Hampshire, Dorset, the the Isle of Wight, Pembrokeshire, South Yorkshire, Lancashire and even Fife. Records of overwintered specimens from 2007 to 2012, appears to indicate that the butterfly is now breeding regularly in low numbers on the Isle of Wight and possibly elsewhere along the south coast. No larvae, however, have been recorded.

When to see

Immigrant adults may be seen in July/August.

Facts

• As well as being larger than the small tortoiseshell, the large tortoiseshell is generally duller, does not have the white marks on the leading edge of the forewings and almost never has blue spots along the edge of the forewings.
• It is thought that climate change and the effects of a virulent strain of the Dutch Elm disease all but eradicated the Wych Elm, the main larval food plant of the large tortoiseshell and thus contributed to its dramatic decline.