The poisonous hairs (setae) of the caterpillar contain the urticating toxin thaumetopoein
The larvae (caterpillars) of the oak processionary moth have poisonous setae and may occur as defoliating pests on oak trees. On contact or inhalation, the urticating toxin from the setae can cause irritations and inflammations to skin, eyes, mucosa and airways.
The oak processionary moth (OPM, lat. Thaumetopoea processionea) is a defoliating pest of oak trees. The oak processionary moth has been spreading throughout Germany for approximately 20 years and is increasingly found in urban areas also. The caterpillars of the oak processionary moth have poisonous setae which pose a health hazard to people and animals because they contain the urticating toxin thaumetopoein. The setae are very small (around 0.2 mm in length, around 0.005 mm in diameter). They will easily break away on contact and can remain toxic for several years. The setae are not only present on the caterpillars themselves which congregate in processionary groups from May to July, but they can also be found on the paths trodden by them and in their exuviae. They are also left in the cocoons which the caterpillars build prior to their pupation. Furthermore, the setae can spread through wind.
Upon contact, the urticating toxin thaumetopoein triggers irritations and inflammations to the skin and mucosa, including eyes and lungs. On the skin, particularly on directly affected areas such as arm, leg, neck and face, swelling and strong itching generally occurs within 24 hours. If untreated, such symptoms last for between two days and two weeks, depending on the degree of contact and the constitution of the individual in question. Inhalation of setae can cause inflammation of airways and breathing difficulties. Conjunctivitis and corneal inflammation can occur following contact with eyes. Systemic complaints such as dizziness, fever, and in rare cases, shock, have also been reported.
PPE should only be used as a protective measure if
We also recommend:
In the event of physical complaints caused by the setae, or their suspicion, contact a doctor. Notify the doctor that EPS setae may be responsible for your physical complaint.
Effective OPM control measures include biocidal treatments against caterpillars and the removal of cocoons.
Caterpillars are treated with chemical or biological biocides, ideally between hatching and third instar. Poisonous setae are present on caterpillars from third instar onwards. There are up to six instar stages until pupation. Further protective measures may be necessary in addition to the protective measures stated above.
In general, the following applies: Cocoons should be removed using a vacuum cleaning system (dust class H, possible pre-separator), as this reduces the risk of rendering setae airborne in comparison with other procedures.
The Federal Environment Agency has further information on the oak processionary moth, on protection against the caterpillars' setae and on control of the oak processionary moth.