News: Spring/Summer 2006
New garden pest bothers gardeners
Appeared on Space For Nature on April 18th 2006
A relative newcomer to the British beetle fauna has emerged from nowhere to end up at 'number 4' in the RHS list of top garden pests for 2005.
The rosemary beetle (Chrysolina americana) is a native of southern Europe but became established in southern England only in the 1990s and has mounted a relentless surge since then. The beetle has a particular liking for rosemary (Rosmarinus officinalis), sage (Salvia sp.), thyme (Thymus sp.) and lavender (Lavendula sp.).
Andrew Halstead, principal entomologist at the RHS, said: "Unfortunately, it appears that this year's newcomers are going to cause problems for gardeners for a while to come. Occasionally, we encounter an 'outbreak year' for a particular pest, such as last year's woolly beech aphid, which generated a record number of inquiries in 2004 but only six in 2005. However, the rosemary beetle has been steadily spreading across southern England for the past few years and it is likely to continue doing so."
Gardeners can identify the adult beetles by the metallic green and purple stripes on the wing cases and thorax. The grubs are greyish-white with five longitudinal darker lines. Fully-grown larvae can reach 8mm, the same size as the adult beetles.
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