When we moved into this house and planted up the garden with insect-friendly plants, we put in loads of Lavender and Rosemary, hoping one day to attract the Rosemary Leaf-beetle Chrysolina americana. Today I saw the first one in the garden … on Lemon Balm! This is an alien beetle which despite the ‘americana‘ name is a native of southern Europe. It is such a looker that I am happy to welcome it in, in any case it has now become well established since it was first recorded in Britain (at RHS Wisley in 1994): see map here.
It is best to look for it on Rosemary and Lavender but it can also breed on Thyme and Sage. See the Royal Horticultural Society’s Rosemary Beetle Survey webpage for more info and to submit sightings.
The only similar beetle in Britain is the very rare Rainbow Leaf-beetle Chrysolina cerealis which feeds on thyme on the slopes of Snowdon and in Cwm Idwal. I have been up and looked for it but without success. I hope to see it one day but meanwhile it is great to have americana in the garden.