Pine caterpillar osteoarthritis is a seasonal regional outbreak epidemic disease that has been discovered in various provinces in southern my country in recent years. It is a disease that mainly invades the skin, bones and joints. Epidemiological surveys and animal experimental studies have shown that this disease is related to contact with pine caterpillars, so it is named pine caterpillar disease. From the perspective of the incidence, it has been reported in nine provinces in my country, including Guangdong, Fujian, Guangxi, Hunan, Hubei, Anhui, Zhejiang, Jiangxi and Jiangsu. In 1970, an employee of a kiln factory in Jinhua, Zhejiang Province, became ill due to using pine branches with pine caterpillars to burn kilns. This was the earliest reported case in my country. In 1975, there were 4,010 cases in Chaoyang, Guangdong, accounting for 5.54% of the total population. The incidence rate of the population exposed to pine caterpillars is 52.9% to 86.4%. The peak period of onset is summer and autumn, with the highest number in October. The age of patients ranges from 8 months to 84 years old, among which young and middle-aged patients aged 20 to 50 are the most common. There is no difference in the incidence rate between men and women, and it mainly depends on the composition of the population in contact. The areas where the disease occurs are mostly near mountainous areas, mainly areas with pine forests and pine caterpillars. Most cases are caused by cutting firewood, beating pine branches, collecting pine caterpillar cocoons, cutting rice in contaminated rice fields, and students coming into contact with pine caterpillars when going up the mountain for outings. It may also be caused by contact with wild grass, clothing and water contaminated by pine caterpillars.