Purple hairstreak (Favonius quercus)

Photograph of purple hairstreak

Purple hairstreak butterflies are mostly found in oak woods across southern England and Wales, with scattered colonies further north. (Photo: Hildesvini/Wikimedia Commons)

Purple hairstreak is a small but handsome butterfly of oak woodland that spends much of its time in the tree canopy.

Common name: purple hairstreak 

Latin name: Favonius quercus

Appearance

Caterpillars: brown with deeper brown line along back and paler oblique line along each side. It is very camouflaged against brown buds where it nestles so can be difficult to find.

Adults: males have a deep, rich purple sheen; females have a purple mark on forewing. Underside is a silvery-grey, with an orange eyespot on the hindwing. They have a pale streak under their wings which gives it the hairstreak name.

Wingspan: 3-4cm.

Food plants

Caterpillars: leaf and flower buds of English oak and sessile oak.

Adults: mainly feed on honeydew, but will occasionally feed from nectar sources such as bramble.

When to spot them

Can be spotted from early July to early September.

Where to spot them

It's mostly found in oak woods across southern England and Wales, with scattered colonies further north. Recently, though, it's been extending its range, especially in the midlands and south-west Scotland, and even into urban areas such as London.

Step out into your nearest oak wood on a warm July evening, and look skyward. They can be difficult to spot, but if you’re lucky, purple hairstreaks will be out to play. They tend to stay around the treetops, and love nothing more than a game of chase on a summer’s evening – whole colonies can hang out in a single oak. 

Top Woodland Trust woods for purple hairstreak

Purple hairstreaks seem to be spreading north through mainland Britain, and you’ll also find them at Killaloo Wood in County Londonderry, where we are planting 40,000 new trees to create our new First World War Centenary Wood. Purples also reign at Bunkers Hill near Stourbridge in the West Midlands; Willesley Wood, near Ashby-de-la-Zouch in Leicestershire; Hainault Forest in Romford, Essex; Dobshall Wood beside Morecambe Bay in Cumbria; Penn Wood, near Hazlemere in Buckinghamshire; and Owlet, north of Gainsborough in Lincolnshire.

Discover purple hairstreak in other woods too. To find woods near you, type your town or postcode into our search box.

Fascinating purple hairstreak facts

  • Eggs are usually laid singly at the base of a plump oak bud and look like mini sea urchins.
  • Caterpillars rest during the day, and become active at night to feed.
  • The pupae survive the winter in leaf litter and are often buried by ants in the soil.
  • Hairstreaks usually have short tails at the end of their wings which look like antennae. These trick predators into striking the wrong end of the butterfly giving it a greater chance of flying away unharmed.
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Close up of a comma butterfly on a leaf

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