Arborists in south-east England are being reminded to protect themselves this spring and summer from contact with oak processionary moth caterpillar hairs (OPM).     They are also encouraged to help control the pest by reporting sightings to the Forestry Commission, and to take care not to spread the pest when removing oak material from tree surgery sites.   As well as damaging oak trees by feeding on the leaves, the caterpillar can impact human and animal health: contac