| Family | Lycaenidae |
|---|---|
| Subfamily | Theclinae |
| Genus | Favonius |
| Species | quercus |
| Authority | (Linnaeus, 1758) |
| English Name | Purple Hairstreak |
| European Red List 2010 | Least Concern (LC) |
|---|---|
| EU 27 Red List 2010 | Least Concern (LC) |
| European Red List 2025 | Least Concern (LC) |
| EU 27 Red List 2025 | Least Concern (LC) |
| Habitats Directive | |
| Bern Convention | |
| CITES |
The Purple Hairstreak is only found around oaks, its only foodplant. Although the butterflies need food, they do not visit flowers. Instead, they remain near the tree, looking for leaves with a layer of honeydew left behind by aphids. This sugary secretion is the butterflies’ most important source of energy. The eggs are laid at the base of the buds. The small caterpillar has developed by the time winter comes, but it remains in the egg, emerging in the spring to feed on the buds and also on the flowers of the oak. It does not eat the leaves and is sometimes visited by ants of the genus Lasius. When mature, the caterpillars leave the foodplant, and pupate in the moss layer. The Purple Hairstreak has one generation a year.
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