Rosemary beetles, a Mediterranean species, have been observed for the first time in a garden in the North Pennines. The beetles, identified as Chrysolina americana, were spotted in a herb bed among rosemary leaves.
These beetles are described as gleaming, with purple and green striped elytra. They are considered a non-native invasive species in the UK, lacking natural predators. The Royal Horticultural Society is monitoring their spread and has requested sightings.
Rosemary beetles can cause damage to plants in the Lamiaceae family, including lavender, sage, thyme, and rosemary, potentially reducing them to bare sticks. Both the adult beetles and their dull grey grubs feed on the leaves.
The beetles were first discovered living outdoors in the UK in 1994 and have since increased rapidly, a trend linked to a warming climate. They have short wings and prefer to walk rather than fly far.