How to Control Cutworm Pests in Corn Fields

This year is a once-in-a-century year of severe drought. Due to the drought, cutworms have broken out severely in Taiyi Township, Dali City. The cutworm is also called the soil silkworm, earth silkworm, or root-cutting worm. It is a relatively common underground pest. The life cycle of the cutworm is divided into 4 stages: egg, larva, pupa, and adult (moth). The adult's body and wings are dark brown. Cutworms generally cause severe damage as first-generation larvae, and the living and damaging habits of larvae differ by instar. 1st and 2nd instar larvae are active day and night, gnawing the heart leaves or tender leaves; after the 3rd instar they hide in the soil during the day and come out at night to cause damage, biting through the tender stems at the base of seedlings and causing missing plants; after the 4th instar the larvae's resistance to pesticides is greatly increased.

Therefore, chemical control should eliminate the larvae before the 3rd instar. Trapping and killing adults is the best strategy for controlling cutworms and can greatly reduce the number of first-generation larvae. The method is to use blacklight lamps and sugar-vinegar liquid to trap and kill them. Weeds are the main place where adults lay eggs and also an important route for larvae to move onto corn seedlings. Before corn emerges, thoroughly remove weeds and promptly move them out of the field to be used as feed or composted for fertilizer; do not leave them scattered or thrown about. Removing weeds will effectively lower the pest population base. Chemical control is still an important measure for eliminating cutworms at present. When sowing, seed dressing with chemicals can be used: mix 0.5 kg of 50% phoxim emulsion with 30-50 liters of water and dress 350-500 kg of seed. For larvae above the 4th instar, poison bait is more effective for trapping and killing. Dissolve 0.5 kg of 90% trichlorfon in hot water, add about 5 liters of clean water, spray it onto roasted fragrant oil residue, and stir evenly to make it ready. Apply 60-75 kg of poison bait per hectare in the evening.