The processionary caterpillar, Thaumetopoea processionea, caused much inconvenience in the Netherlands in 1996-1997; from the medical point of view, mostly itching and skin rash. After contact with stinging bristles of the caterpillar and with the pesticide Dimilin SC-48, of which diflubenzurone is the active agent, a 72-year-old man had to be resuscitated because of ventricular fibrillation caused by hypotension related to relative underfilling and low systemic vascular resistance. He made a good recovery. Such life-threatening situations can be prevented by publicly announcing plague control measures and closing of the affected areas to the population, with ample margins.