I. Types of corn pests and diseases \x0d\ Corn pests and diseases include corn borer, armyworm, cotton bollworm, aphid, corn spider mite, etc. \x0d\ 1。 Corn borer: Corn borer, commonly known as borer, belongs to Lepidoptera and Coccinellidae and is the main pest of corn. It can harm all parts of corn plants on the ground. Ostrinia furnacalis generally occurs 2-4 generations a year, with high temperature, low altitude and many generations. Adults are nocturnal, with strong flying ability and phototaxis, and their life span is 5- 10 days. They like to lay eggs on both sides of the midrib on the back of corn leaves more than 50 cm above the ground. After hatching, the larvae gather together at first, then crawl in the tender part of the plant and start to do harm. The newly hatched larvae can spin silk and droop, and float to neighboring plants with the wind, causing transplanting hazards. \x0d\ 2。 Myxomycetes: Myxomycetes, commonly known as multicolored insects and wheat silkworms, belong to Lepidoptera Noctuidae. It is the main pest of food crops and feed crops, which seriously harms corn. The armyworm is a polyphagous, migratory and explosive pest. The occurrence of armyworm is closely related to temperature and humidity. Generally, the optimum temperature for adults to lay eggs is 19-25℃, and laying eggs above 30℃ is affected. In addition, the greater the humidity, the more favorable it is for adults to lay eggs, especially in rainy and humid climate conditions, which is not only beneficial for adults to lay eggs, but also conducive to the hatching of eggs and the survival and development of larvae. \x0d\ 3。 Cotton bollworm: Lepidoptera, Noctuidae. Alias borer, caterpillar, cotton bollworm, etc. \x0d\ 4。 Corn aphid: It can harm many gramineous crops and weeds. At seedling stage, adult aphids and nymph aphids cluster in the heart leaves, which damage the ear after heading, suck juice, hinder growth, and can also spread a variety of Gramineae cereal viruses. Its secretion will stick to pollen and affect loose pollen. In addition, it can also spread maize dwarf mosaic virus disease, resulting in different degrees of yield reduction. \x0d\ 5。 Corn spider mite, commonly known as red spider, can harm many crops. Adult mites and nymph mites suck the sap of the back tissue of the host leaves, and the damaged leaves turn from yellow to white and die, which affects the filling process of corn, resulting in the decrease of 1000-grain weight and yield. \x0d\ II。 Control method \x0d\ 1. Use 2.5% of cypermethrin for 2000-2500 times, or use 20% of tebufenozide suspension 1000-2000 times, or use 25% of it for 100 times. \x0d\ 2。 Spraying plants with 2% avermectin 3000 times solution can control corn spider mites. \x0d\ 3。 Spraying plants with 3% acetamiprid 1500 times solution or 2% avermectin 3000 times solution can control corn aphids and Laodelphax striatellus. \x0d\ 4。 In the big horn period of corn, 0.25 kg of 30% phoxim granules and 2 kg of fine sand were mixed evenly per mu, and 2-3 g of corn borer was sprayed on each plant to control corn borer.