Shiny invaders

Rosemary Beetle (Chrysolina americana)

Whilst checking the herb garden during a coffee break this week, Mike chanced upon our first Rosemary Beetles (Chrysolina americana), a handful of which were trundling across sage leaves or huddled on rosemary stems. We've been expecting them, to be honest. Though they weren't recorded in Britain until the late 1990's (when they were found breeding in central London), they have now spread right across the British Isles and are common and widespread in England and Wales. Their iridescent purple and green stripes make them easy to identify despite their small size; they measure only 6–8 mm (about a third of an inch). Though they nibble on the flowers and leaves of rosemary, sages, thymes and other aromatic plants, they don't typically cause too much damage, and even the Royal Horticultural Society suggests they be considered as "part of the life a healthy garden supports". Apparently, the larvae, which generally occur in late summer, are rather more voracious than their parents (which may feed little until they're ready to mate). Adults can be reasonably long-lived for a beetle, regularly surviving more than a year. Despite their scientific name, the beetles didn't originate in the Americas. Rather, they're from southern Europe – presumably yet another indication of a changing climate.