AN ARMY of hungry and very toxic caterpillars is on the march - expanding its empire across Britain. The annual invasion of the caterpillars - the larvae of oak processionary moths (OPM) - has now began in earnest. The critters first arrived in the UK in a shipment of oak trees from Holland to London in 2006.
But a new map released by the Forestry Commission shows how they have spread to the home counties and beyond in the past 18 years. Taking Trafalgar Square as the centre of London, the bugs are fully established 26 miles north to Welwyn Garden City, Hertfordshire, and 50 miles south to Dorking in Surrey. They have also crawled their way 30 miles west to Windsor and Maidenhead in Berkshire, and around 30 miles to the east, almost reaching Southend-on-Sea in Essex.
These four points mark out the 'infected' or 'established' zone - where the pests are already 'bedded in' - which is expanding at around five-miles-a-year. The surrounding area is called the 'buffer zone', and is where there have been sporadic appearances of the pests. The buffer zone extends to Bedford to the north, 60 miles from Trafalgar Square, and to Eastbourne and Worthing to the south, around 60-70 miles from the capital.
The zone reaches almost 80 miles to Swindon, Wiltshire , to the west, and almost reaches Canterbury in Kent, 60-odd miles to the east. Outside these two zones is a 'new zone' - a 'movement exclusion zone' - created last year, which outlaws oak trees being moved out of either the infected .
