September 27, 2025

Holly blue

Holly blue butterfly feeding on purple loosestrife

Holly blue
Celastrina argiolus

Conservation status: Common

When to see: April to September

About

The holly blue butterfly is a charming butterfly usually seen in early spring, from March to May, and again at the end of summer, between July and September. This beautiful blue butterfly is commonly found in gardens, woodlands, parks, and churchyards. Unlike other grassland blue butterflies that fly low to the ground, the holly blue prefers to soar high around bushes and trees. The caterpillars of the holly blue butterfly feed on a variety of plants, including Holly (spring generation) and Ivy (summer generation). However, they also enjoy a wide range of other plants, such as spindle and bramble, and in this case purple loosestrife.