| Family | Lycaenidae |
|---|---|
| Subfamily | Theclinae |
| Genus | Thecla |
| Species | betulae |
| Authority | (Linnaeus, 1758) |
| English Name | Brown 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 Brown Hairstreak occurs in scrub, along woodbanks at the edge of deciduous woodland, and in parks, but the butterfly is rarely seen. However, the eggs that are laid at the base of the buds of various Prunus species are easy to find. In the winter the pearly-white eggs show up on the bare twigs of the shrubs or trees. The egg, thus, hibernates, hatching in the spring. The small caterpillar bores its way into a bud, hollowing it out, later on also eating the leaves of Blackthorn (Prunus spinosa), but also cultivated species of Prunus, such as plum and cherry trees. The caterpillars are visited by ants of the genera Lasius and Formica. They pupate in the shrub layer under the tree serving as foodplant. This butterfly species is single-brooded.
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