Home The Butterflies of Gloucestershire Species Habitats Conservation

Holly Blue

Celastrina argiolus
Female, 20 May 1990 Male, 4 September 1977


Holly blues may be seen almost anywhere. Eggs are laid on flowers or buds of various shrubs, particularly Holly by the spring generation of adults and Ivy by the summer generation. Hedgerows and woods provide suitable habitat, as do many gardens.

Conservation Issues

As the Holly Blue population builds up to a peak over several years, so too does the population of a parasite which eventually causes a crash in the populations of both. The cycle then repeats.

This effect is very noticeable. In some years Holly Blue is one of the commonest species recorded, but after a population crash there are very few records of the species.

With both holly and ivy being grown as garden plants, there is plenty of habitat for the species in towns in addition to the open countryside.

Flight Period

April and May for the spring generation (with some seen in March after mild winters). July to late August for the summer generation, and perhaps a partial third generation in late September or October.


Throughout the area