In ecological terms, changes in insect populations are affected both by "biological factors," such as their natural enemies and host plants, and by "environmental factors," such as weather, soil and man-made pollu tion.
根據生態學上的推測，影響昆蟲族群變動的因素，除了天敵、寄主植物等「生物因子」，氣候、土壤、人類汙染等「環境因子」往往才是蟲子大發生的主因。