在经济昆虫的分类中,除了系统分类方法外,人们往往根据昆虫取食、危害对象和作用而区分为农业害虫、林业害虫、医学昆虫、资源昆虫等数类。但昆虫如同其它生物一样,与周围环境条件有着密切联系,具有良好的适应性。对某些种类害虫,在其分布区内,常常能适应多种食物的变化,特别是一些杂食性害虫,甚至某些单食性害虫,在缺乏其所嗜好的食物时,也可取食其它非嗜好的食物。还有些害虫由于对食物等条件的要求,而引起有规律的季节性的迁移。所以按害虫取食、危害的对象和作用而分成农业害虫和林业害虫,也只是相对的。在一定条件下,农林害虫可以交叉危害,并造成严重的经济损失。 In the classification of economic insects, except for systematic classification methods, people are often divided into agricultural pests, forestry pests, medical insects, resource insects and the like according to insects feeding, harming objects and functions. However, insects, like other organisms, are closely linked with the surrounding environment and have good adaptability. For some species of pests, in their distribution area, often can adapt to a variety of food changes, especially some omnivorous pests, and even some pests, in the absence of their favorite food, you can also eat other non- Hobby food. Some pests also cause regular, seasonal shifts due to food and other conditions. Therefore, according to the pests feeding, endangering the role and role of agricultural pests and forestry pests, only relative. Under certain conditions, agricultural and forestry pests can cross hazards and cause serious economic losses.