The armyworm belongs to lepidopteran pests and its diet is very complex. It is a leaf-eating pest that can harm more than 100 species of plants. The damage on summer corn is mainly eaten by the larvae to eat the corn leaves. When they occur, they can eat up the stems and leaves of the crops, resulting in reduced yields and even no harvest. Due to its characteristics of polyphagia, migration, and fulminantness, it often causes sudden outbreaks in local areas. In recent years, most of the summer maize in the south-central province of our province has been planted with pods, which is extremely conducive to the hatching of egg worms in the summer corn field. In addition, high residual sorghum is left by the mechanical harvesting of wheat, and the amount of residual wheat stalks in the field is large, making the second generation. Mythimna separata larvae hide under wheat straw and harm young maize shoots that have just been unearthed. Severe years can cause destructive breeding. I. Occurrence characteristics Adult insects of the armyworm have the habit of migrating from long distances. In the spring, they gradually migrate from the south to the north. In the fall, they fly back from the north and fly back to the south. In the middle and southern part of our province, it took 3 to 4 generations a year. Adults lived overnight and grazing at dusk. Adults have strong tendencies toward lighting, sweet and sour liquids. Females tend to lay eggs in the dry leaves, in the corn seedling eggs produced in the tip of the leaves, adult plants in the temporal lobe or ear spikes, etc., the formation of vertical strips of egg mass, each egg block 20 to 40, many Up to 200 to 300 tablets. Each female produces 1000 to 2000 eggs. Mythimna is like wet climate, relative humidity more than 75%, temperature 23 °C ~ 30 °C is conducive to adult oviposition and larval survival. The larvae have six instars, and the larvae of the first to second instar are mostly hidden in the heart of the crops, and feed on the leaves, leaving only the epidermis. After 3rd age, the leaves bite into irregular nicks. When the density is high, the leaves can be eaten to leave only the leaf veins. After 4th instar, the larvae were suspended dead and entered the binge-eating stage. When the big larvae occurred, they had the habit of cluster transfer hazards. After larvae matured, they stopped feeding and climbed into soil layers of 3 to 4 cm in order to remove soil maggots. Second, prevention and control measures in the summer corn seedling stage is mainly the second generation of adult mythimnasis larvae damage, when the summer corn just emerged, often can eat seedlings. Therefore, as long as the summer corn seedlings are found to be affected by the armyworm, they need to be prevented and treated in time. 1. Protection and use of natural enemies: There are many types of natural enemies of the armyworm, and there are certain natural control effects on the occurrence of armyworm, such as frogs, birds, bats, spiders, predatory insects, parasitic bees and so on. 2. Physical and artificial measures: Insert a 5 cm diameter grass handle in the field during the adult period, insert one every 10 meters, and use a plastic bag to cover the grass every morning to kill the armyworm that lurks in the grass handle. Moths. Can also be set in the field sweet and vinegar trap adult insects, basin distance of about 500 meters. Preparation of sweet and sour liquid: 1.5 parts of brown sugar, 2 parts of edible vinegar, 0.5 parts of white spirit, 1 part of water, plus proper amount of trichlorfon or other insecticide. 3. Biological control: younger larvae use 20% diflubenzuron (diflubenzuron 1) suspension agent 10 grams per acre, or 25% diflubenzuron (diflubenzuron No. 3) suspension agent per acre with 25 to 30 grams, spraying water, or using Bacillus thuringiensis WP 50 g/mu, conventional spray on water. 4. Chemical control: The summer corn field that is sown and planted can be mixed with poison bait. Mu with 90% trichlorfon 200 grams, stir fry bran or fry 10 kg of cotton cake, early in the evening with the corn line spread for trapping. Spray control can be used 2.5% Kung Fu EC 3000 times, 4.5% Beta-cypermethrin EC 1500 times, 48% chlorpyrifos EC 1000 times, one of the above-mentioned agents, spraying liquid volume per acre 40 to 50 kg. When the worm age is large, it is necessary to appropriately increase the dosage and the amount of water sprayed. Spray time is best selected in the morning or evening to improve control efficiency.
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