British Wildlife Wiki
Holly Blue

Holly Blue - Dave Skingsley

The Holly Blue (Celastrina argiolus), is a butterfly that belongs to the Blues family and is native to Eurasia and North America. This butterfly is very small blue butterfly with a few small black spots across its wings and a black border that is more pronounced in females. The undersides of the wings are pale blue. The body is blue and covered in long hairs. The antennae are black with small white stripes along their length. This butterfly appears slightly silvery when in flight

Male holly blues have sky-blue upper wings with narrow, black borders, whereas females have broad, dull black borders. In both sexes the under wings are palest blue, almost white, with black spots.

It is relatively common in the south and Midlands, but more rare farther north: numbers fluctuate from year to year.

In spring females lay their eggs at the base of flower buds on holly bushes. Later in the year females use ivy bushes, as well as sometimes spindle, dogwood and heathers.

The caterpillars are usually green, but some may be camouflaged with pinky stripes. Caterpillars are often easy to find as they leave conspicuous holes where they have munched the flower buds. They probably pupate on or near the ground and are likely to be tended by ants. This species overwinters as a chrysalis, with adults emerging in April.


Holly blues are widespread throughout Britain and Europe. They are also found in Asia, North Africa and North America

The Diet Of The Holly Blue[]

The spring brood of caterpillars feed on holly, whereas the summer brood feed on ivy. Caterpillars also feed on gorse and bramble. Adults tend to feed on the flowers of ivy and holly.

Adults drink oozing sap, aphid honeydew and carrion juices. Caterpillars usually eat holly and ivy, but also dogwood, spindle and heathers.


This species has two broods in the summer. The first, in the spring, feed on holly and when they become adults and have mated they lay their eggs on ivy plants. The ivy brood overwinter as crysalids and emerge in the spring to mate and lay their eggs on holly

Conservation Status[]

Holly blue populations tend to fluctuate between the years and have been very scarce in some years. They are currently abundant and are not listed as endangered

When will we see this butterfly?[]

Adults between April and June then August and September. Caterpillars between May and June then August and September.

Where will we see this butterfly?[]

Generally high up near the tops of bushes. Basking in sunshine with shut wings. Caterpillars on holly and ivy flower buds. Also in parks, hedgerows, woods.