Oak processionary moth

The oak processionary moth is a brown-grey butterfly that flies from the end of July to the beginning of September and is harmless to humans. However, the caterpillars of the butterfly, which are considered a pest, pose a considerable danger to humans. They hatch at the beginning of May, attack individual trees (mainly oaks) and feed on their foliage. They go through up to six stages of development before pupating at the end of June/beginning of July. In mid-June, the older caterpillars retreat into webbed nests during the day to moult. From there they go in search of food.

The caterpillars' stinging hairs with their characteristic nettle venom and barbs are particularly dangerous to humans. These can trigger itchy, inflammatory skin rashes, redness, wheals and blisters (caterpillar dermatitis), rashes or even allergic shocks. Fully-grown caterpillars have around half a million stinging hairs, which break easily and are thus carried through the air by the wind. As a preventative protective measure, you should avoid direct proximity or direct contact with the caterpillar and its nests. The spun nests in which the stinging hairs remain pose a danger for years to come. Avoiding contact as a basic protective measure also applies to pets such as dogs or free-roaming cats.

If you notice an infestation in your garden, you should have it controlled by professionals (pest controllers or arborists), as the stinging hairs can easily be whirled up, increasing the risk of injury to you and those around you. It is therefore not advisable to carry out the control yourself. Private individuals are not obliged to report oak processionary moths, but it is recommended that they do so.