Complex sentence: The Oak Processionary "(Thaumetopoea processionea)" is a moth whose caterpillars are pests in oak forests and pose a health hazard because of their poisonous setae (hairs), which may cause skin irritation and asthma.
Split into simpler sentences: The Oak Processionary "(Thaumetopoea processionea)" is a moth whose caterpillars found in oak forests. They may pose a human irritant because of their poisonous setae (hairs), which may cause skin irritation and asthma.