Is the Rosemary Rainbow Beetle Chrysolina americana at large in Worcestershire?

Gary Farmer

During a visit to Snowshill Lavender near Broadway my son found several metallic, striped beetles. I had seen this species once before (in Solihull) and so could immediately identify them as Rosemary Rainbow Beetles Chrysolina americana.

This species is beautiful but feeds on the leaves of Rosemary, Lavender, and related plants and it appears that some species in the Lamiaceae family can also be hosts.

The beetle grows to around 8mm long and is metallic green with purple stripes and so is very distinctive.

The beetle is a native of southern Europe and was first found living out of doors in the UK in Surrey in 1994 and by 1998 established colonies of the beetle had been discovered near London’s Waterloo Station and near Reading, Berkshire. By the end of 2005 the beetle had become widespread throughout London and surrounding areas. Rosemary Beetle is now widespread in England and has been found in parts of Scotland, Wales, Northern Ireland and the Irish Republic.

I sent a record off to Gloucestershire BRC and received the following response:

“The Rosemary Beetle seems to be cropping up quite often this year; a lady reported some from the middle of Cheltenham recently. They are beautiful but not the gardener's friend, as they really do eat Rosemary, often stripping whole bushes of leaves. Unfortunately for Cotswold Lavender, they also eat Lavender leaves.… it's awkward to treat them as any insecticides are highly likely to affect bees. I notice that Mayfield Lavender Farm in Surrey are giving out jars for people to collect the beetles as they look around the fields, rather than risk spraying.…”

The Royal Horticultural Society is keeping track of the spread of rosemary beetle at the moment: http://www.rhs.org.uk/Science/Plant-pests/Rosemary-beetle.

Having found this species to the north east and south of the county I do wonder if it is lurking somewhere in Worcestershire maybe in a garden near you. This is certainly one to watch for in the future.

Images

Fig. 1. Rosemary Beetle Chrysolina americana 15.07.12 Snowshill Lavender. Gary Farmer

Fig. 2. Rosemary Beetle Chrysolina americana 24.08.08 Malvern Park, Solihull. Gary Farmer