西北农林升技大学 1.Concept of Agri. Entomology *Many pests can damage crops growing in fields. *Stored crop grains,harvested after crops are grown,can be damaged by pests. *Pests can mainly be divided into 6 categories: Crop diseases Pest insects Weeds Rats Birds Beasts(eg.wild boar） 8888 3 3 1. Concept of Agri. Entomology Many pests can damage crops growing in fields. Stored crop grains, harvested after crops are grown, can be damaged by pests. Pests can mainly be divided into 6 categories: Crop diseases Pest insects Weeds Rats Birds Beasts (e.g. wild boar)