Holly Blue | Reserves and species

Scientific Name:

Celastrina argiolus

The Holly Blue is a small blue butterfly which flies in the spring, from March to May, and then again at the end of the summer between July and September. This is the blue butterfly most likely to be found in gardens, as well as woodlands, parks and churchyards. The foodplants of the caterpillars are mainly Holly (for the spring generation) and Ivy (for the summer generation), although a wide range of other plants are used including Spindle, Bramble and Gorse.

How to identify:

The Holly Blue is a bright blue butterfly with silvery underwings dotted with small black spots. Females have black wing edges. It is smaller than the very rare Large Blue, and a lot larger than the tiny Small Blue. It is easily distinguished from all the other blues by the silvery underside completely lacking in orange spots.

Where to find it:

Found in England, Wales and scattered places in Northern Ireland, but absent from Scotland.

How people can help:

Butterflies such as the Holly Blue will happily visit your garden and are a joy to watch. To attract butterflies into your garden, plant nectar-rich borders for them to feed along and climbing Ivy and shrubs for overwintering insects. To find out more about encouraging wildlife into your garden, visit our Wild About Gardens website: a joint initiative with the RHS, there's plenty of facts and tips to get you started.

Statistics:

Wingspan: 2.6-3.4cm

Conservation status:

Common.

Did you know?:

Holly Blue populations fluctuate enormously from year to year as they are parasitised by an ichneumon wasp which kills the larval stage. In turn, the decreased number of adults affects populations of the parasite, allowing time for Holly Blue populations to recover and the cycle to start again.

Seasons:

Spring

Summer

Autumn

When to see

Start date:

March

End date:

September

Image: