Oak Processionary Moth: Recognising It & Safe Removal

Nests are grey-white, web-like clumps against the trunk or thicker branches of oak trees, often with visible shed skins and droppings. The caterpillars themselves are greyish-brown with dense, fine hairs. The dangerous window runs roughly from mid-May to June, when the urticating hairs appear; spread via wind and contact can continue into July, August and sometimes September, even from nests that look empty.

A single caterpillar carries over 700,000 microscopic hairs with tiny barbs that easily penetrate skin, eyes and airways:

• Skin: irritation and rash, often visible within 8 hours, can itch for up to 2 weeks.
• Eyes: redness, pain and swelling, sometimes within a few hours.
• Airways: irritation of the nose, throat and airways when inhaled.

Because the hairs also spread on the wind, cutting or spraying a nest yourself without protective clothing and a respirator is risky, even at some distance from the nest itself.

Certified companies vacuum the nest, hairs included, with an industrial specialist vacuum and dispose of the sealed bags according to regulations. Preventively, nest boxes for great tits help: the birds eat young caterpillars and reduce pressure in later years. We are happy to include this kind of prevention in your garden maintenance, but leave the actual removal of a nest to a certified pest control company - that requires protective equipment and gear that falls outside regular gardening and tree-care work. We are glad to advise and coordinate this for you.

For trees in public spaces, the municipality usually deals with nests itself - report one via your municipality's public-space reporting point. If the oak is in your own garden, you are responsible and need to arrange a certified pest control company yourself; the municipality does not handle this for private trees.