This dataset contains a long-term record of tree (Pinus sp.) defoliation by pine processionary moth (Thaumetopoea pityocampa) in a series of pine forest plots distributed throughout the Granada province (SE Spain). The plots are part of a monitoring network, aimed to study the phenology and intensity of defoliation by this lepidopteran, that occasionally causes severe defoliation in Mediterranean pine forests. The file includes descriptive features of the plots as well as annual records of defoliation and population size.