Harmful symptoms:
Common ground tigers are small ground tiger, earth tiger, yellow ground tiger and eight-character ground tiger, among which the harm of small ground tiger to corn is the most common and serious. Distributed all over the country, it is a typical omnivorous pest with a wide range of host plants. Except for a few aquatic plants such as rice, it can feed on the seedlings of almost all plants, especially corn, cotton, beans, sesame, tobacco, vegetables, etc., which is seriously damaged, leading to seedling shortage, ridge breakage and even seed destruction. After corn seedlings are killed, they often need to be replanted many times, even replanted, which is labor-consuming and time-consuming, and even reduces production.
Occurrence law:
It has 4-5 generations a year (2-3 generations in high and cold areas), overwintering with larvae and pupae, but not in Huanghuai River basin. Overwintering adults move in from the south, and the first generation larvae are the most harmful. Adult, nocturnal, sweet and honey-loving, phototactic and migratory, tends to lay eggs on weeds. A female moth lays about 1000 eggs, and the eggs are scattered or integrated into a small piece to form a line. Eggs hatch after 5-7 days. Larvae, generally 6 years old, feed on mesophyll on leaves day and night, leave the epidermis, form pinhole-shaped flowers and leaves, or eat young tissues into notches; After the third instar, they live in the soil during the day and move at night, or eat leaves in large pieces, or eat the base of young stems, or eat young stems from the roots; 5-6 years old, entering the gluttony stage, eating a lot, causing rampant harm. Larvae have the habit of transplanting, so it will cause a lot of seedling shortage. The larvae mature and pupate. High temperature is not conducive to the occurrence, such as cool and humid, large field coverage, overgrown weeds, high soil moisture and many insects, which will aggravate the harm. Sandy loam and clay loam are heavy and sandy soil is light.
Prevention and control methods:
Weeds in the fields can kill some eggs and pests. Transplant healthy seedlings at the right age to prevent young larvae from hurting them. Trapping and killing prevention, using sweet and sour liquid and black light to trap and kill adults at the early stage of adults.
Before the 3rd instar of larvae, when the seedlings begin to suffer from symptoms, the following drugs can be used: 2.5% trichlorfon powder 2-3 kg/mu; 75% phoxim EC 1L/ mu is sprayed with a small amount of water, 250-350kg of fine soil, and15-20kg of medicinal soil per mu is sprayed on the base of corn seedlings; Spraying 90% crystal trichlorfon with 1000 times solution has a good effect.
Poisonous bait should be used to trap and kill larvae after the 4th instar. The following formula can be adopted: 90% crystal trichlorfon 1 kg/mu, 5- 10 kg of water, 60-70 kg of chopped fresh grass leaves, and 0/5-20 kg of poisonous weeds per mu; 50-year-old mu of 90% crystal trichlorfon, 75% phoxim 50g/ mu,1-1.5 kg of water, mixed with cottonseed cake, 2-3kg per mu, and sprinkled in the seedling base at night; Spray 2.5% deltamethrin or 20% fenvalerate emulsifiable concentrate evenly with 2000 times of liquid; 500 ml of 40% methyl isofenphos emulsifiable concentrate, add appropriate amount of water, and spray 50 kg of fine sand; 1 part 50% methamidophos or 50% dichlorvos, mixed with 100 part fine sand, 20-25 kg toxic soil per mu, and spread along the ridge near the roots of corn seedlings. Or 500g of 90% crystallized trichlorfon and 5kg of cottonseed cake; 500 grams of 2.5% trichlorfon powder, 50 kilograms of fresh vegetables, 5 kilograms of poisonous bait per mu, or 0/5-20 kilograms of poisonous weeds/kloc-are scattered among the corn rows at night.