GARDENERS need to defend their herb beds as the onward march of the rosemary leaf beetle continues.

This herb-munching menace created a record number of inquiries to the Royal Horticultural Society advisory service in 2005 and has shot up the ranks of the UK's most troublesome pests to become the fourth most inquired about pest last year.

Leatherjackets, the bane of lawn lovers, are also a new entry into the top ten with a record number of inquiries.

However, they did not upset the usual suspects at the top of the RHS list of inquires made to the RHS Entomology Department in 2005. Slugs and snails reclaimed their position as gardening enemy number one as they hit the top spot for the third time in five years. Lily beetle and vine weevil, last year's joint number ones, were second and third respectively.

Principal entomologist for the RHS Andrew Halstead 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 beetles has been steadily spreading across southern England fort he past few years and is likely to continue doing so."

However, it seems that south Worcestershire has escaped their attention so far.

Liz Nicklin, of Harrells Hardy Plants Nursery in Albert Road, Evesham, said: "I have been told that this is a problem in some places and we have checked.

"So far, however, there are no signs that it has reached this part of the world. lily beetle, on the other hand, which had caused problems in the south in previous years, has spread to this area."

The rosemary beetle, which originates from Southern Europe, became established in southern England in the 1990s. Both adults and larvae eat the foliage of rosemary, lavender, thyme and sage. Gardeners can identify the adult beetles by the metallic green and purple stripes on the wing cases and thorax.

Mr Halstead said: "Rosemary beetle can be controlled either with insecticides or hand-picking. Unfortunately, there are no recommended insecticides that can be used if herbs are to be used for culinary purposes.

A one-to-one advisory service is available to RHS members but anyone can access advice and information by visiting www.rhs.org.uk/advice/index.asp.