New legislation: Oak processionary moth (OPM)

14 August 2018

Defra has introduced legislation, which comes into force on Tuesday 21 August 2018, to protect oak trees against the imminent danger of introducing Thaumetopoea processionea (oak processionary moth-OPM) into the OPM Protected Zone through import and movement - OPM is an established pest in London and surrounding areas, but the majority of the UK is a designated Protected Zone.

The legislation applies to oak trees (Quercus L), other than Q. suber, with a girth at 1.2m above the root collar of 8cm or more. Such trees represent the greatest likelihood of introducing OPM, hence the need for strengthened requirements. Existing requirements on OPM freedom continue to apply for trees with a smaller girth than 8cm.

The legislation prohibits the movement of plants into the OPM Protected Zone unless specific conditions are met.

Details of the conditions can be found at

For more on oak processionary moth, visit