The Forestry Commission has issued a warning over toxic caterpillars which could be in Essex.

Oak processionary moths (OPM), are currently in their larval stage and have been spotted across the south-east of England and in London.

Hairs on the caterpillars can cause fevers and eye and throat irritations, and the Forestry Commission is warning people not to touch the species.

They have been previously spotted in Thurrock and in the Epping Forest area.

Alison Field, the Commission’s South East England Director, said: “We are working hard to protect our oak trees from the devastating effects that large numbers of these caterpillars can cause. To help us to do this, we are asking anyone who spots the caterpillars or their nests to contact the Forestry Commission.

“However it’s vital that members of the public avoid any contact with the caterpillars or the nests. The treatment of infested oak trees needs to be carried out by specially trained experts and treatment must be carefully timed in order for it to be most effective.”

Brentwood Live:

Credit: The Forestry Commission

OPM caterpillars

  • move about in nose-to-tail processions;
  • often form arrow-headed processions, with one leader and subsequent rows containing several caterpillars abreast;
  • are most likely to be found in oak trees;
  • are most likely to be seen in summer;
  • have very long, white hairs which contrast markedly with other, shorter hairs;
  • and do not live on fences, walls and similar structures, as some caterpillar species do.

OPM nests

  • are usually roughly semi-spherical or teardrop-like in shape before they begin to collapse, when they can become bag-like;
  • occur almost exclusively on oak trees;
  • are almost always attached to the trunks or branches of oak trees;
  • and are almost never woven among the leaves.
  • Silken webbing nests among oak leaves, or in other trees and shrubs and on other structures, are almost certainly NOT made by OPM and need NOT be reported.

If you spot any caterpillars or nests affecting oak trees in your area you can contact the Forestry Commission on or call 0300 067 4442.

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