Seating Area ‘tidy up’ operation Posted on 02/09/2023 September 1st 2023 Along the Thames Path between Hampton Court and Richmond these oaks are being checked for procession caterpillars and the bag contains samples. The oak processionary moth was accidentally introduced to London in imported oak trees in around 2006, and has since spread around the southeast. As well as being a pest of oaks, its caterpillars can cause irritation and, in serious cases, allergic reactions for people and animals.