Finally, I’ve seen my first butterfly of the year, a beautiful blowsy brimstone fluttering from the churchyard towards my neighbours garden. It quite lifted my spirits. It is commonly believed that the word “butterfly” refers to a butter coloured fly – quite likely the brimstone butterfly
The brimstone hibernates through the winter, often amongst the leaves of ivy, holly or brambles, and emerges in March or April when the weather is a little less inclement. It is common in the south of England and the midlands but seen less often in the north of the country, simply because the only food plants eaten by its caterpillars were not historically used as hedgerow plants in t’north.
This is a prime example of butterflies whose children are fussy eaters. The brimstone caterpillar is bluish green, covered with small black spots and has a pale line along its sides. It feeds on buckthorn and only buckthorn. The adults will fly up to 15 miles to find a bush to lay its eggs on….an impressive distance for a creature with a 5 cm wingspan.
Purging buckthorn Rhamnus catharticas is a native shrub that features on the RHS Perfect for Pollinators list. The only other species the brimstone can use is the Alder buckthorn Frangula alnus.
These two shrubs were once cultivated to supply charcoal for gunpowder. Both have greenish white flowers that appear in May and are a source of nectar to honeybees and bumblebees and butterflies as well as flies.
Of course the adult brimstone butterfly cannot be expected to starve itself from the time it emerges from hibernation until the time that the buckthorn flowers….instead you’ll find it fluttering around lanes, field margins and gardens enjoying whatever nectar it can find. It’s important then that we ensure suitable nectar rich flowers are available from early spring onwards. Autumn nectar plants are vital to these creatures as they need to build up their fat reserves in preparation for winter hibernation.
Adults feed primarily on Thistles, Betony, Bluebell, Bugle, Cowslip, Dandelion, Knapweeds, Wild Marjoram, ragged Robin, Red Campion, Selfheal and Vetches – many of these species are found in Meadowmat wild flower matting. So if you want to attract Brimstone butterflies to your garden, a small area of wild flower meadow would be no bad thing.