A rainbow in the garden

This is a Rosemary Beetle, Chrysolina americana, a beautiful little beetle about 7mm long, with superb metallic colouring. It originates from southern Europe and has been found in Britain since the mid-1990s, gradually spreading from the London area. Here it is on lavender in my garden. Apparently it strikes fear in gardeners and the Royal Horticultural Society have listed it in their top ten unwanted garden pests...but I've been seeing the odd one amongst my herbs over the last 3 years and it hasn't so far proved to be a problem. Difficult decision if it gets out of hand, but I don't think I could bring myself to destroy a rainbow!