Among the local tiger families, local tigers are widely distributed and numerous, which have occurred and harmed all over the country. 1 year is a little different from place to place, generally 3-5 generations, and each generation is 6 years old. 1-2-year-old larvae often gather on the heart leaves or back leaves of seedlings to feed on mesophyll, leaving a layer of epidermis, or biting into small holes or nicks, which is not easy to be found because of small food intake. Larvae after the 3rd instar lurks under the topsoil or in the shade during the day, bites the tender stems at night, and drags the tender heads into soil holes to feed. It is obviously harmful to enter the gluttony period after the age of 4. Black cutworm adults like to eat sweet and sour liquid, fermented products, nectar and aphid excrement. In early spring, due to the serious occurrence of aphids in vegetable stubble, there are more rotten fermentation products in rape stubble, which has a strong trapping effect on black cutworm adults and a high amount of eggs laid in the field. Planting soybean cutworms on this stubble is generally more harmful.
Black cutworm, adult 16 ~ 23 mm long, taupe. Mature larvae are 37 ~ 50 mm in length, with yellowish brown to dark brown head, dark gray body and dark longitudinal bands on the back. The body surface is rough and densely covered with black circular protrusions.
The overwintering state of the ground tiger varies with different species. Many species overwinter with mature larvae or pupae, such as the striped cutworm and the eight-character cutworm. Some species overwinter with egg-shaped larvae, such as the white-edged ground tiger. The status of overwintering insects of the same species often changes with different climatic conditions in different regions. Some species overwinter in low temperature areas and do not overwinter in warm areas. For example, the black cutworm can continue to grow and breed in winter south of Nanling; In the north of Nanling, you can safely overwinter; In the area north of Jianghuai, the survival rate of overwintering in the field is very low. Overwintering sites are mostly below the surface, and the depth varies with the temperature in different regions.
The comprehensive control of cutworm includes (1) agricultural control: ploughing and freezing in time after harvest, which makes the soil loose and is not conducive to the overwintering of larvae in the soil; Remove the wild litter and weeds as the spawning ground of the black cutworm; Combine intertillage and weeding at the seedling stage of crops to eliminate eggs and larvae. (2) Trapping and killing: Before the crops emerge, pile some fresh vegetable leaves in the field every 3-4 meters to trap the larvae, and turn over the leaves every morning to kill the larvae. For older larvae, the topsoil near the bitten seedlings can be removed in the morning to catch them; The adults were trapped and killed with sweet and sour solution (3 parts of brown sugar, 4 parts of vinegar, 0/part of wine/kloc-0, 0/part of water/kloc-0, mixed with 0. 1% dichlorvos emulsion). Pour the sweet and sour liquid into the trap prepared in advance and support it with a tripod at a height of 1 m above the ground. One trap is usually placed per hectare. Straws made of bamboo, rice or wheat stalks are inserted into the ground to lure adults to lay eggs, and they are replaced every five days 1 time, and the straws are burned intensively to eliminate eggs. (3) Chemical control: toxic soil: before sowing, use 0.5 kg of 50% phoxim every 667 m2, add appropriate amount of water, spray and mix 30 kg of fine soil, and scatter it near the rhizosphere of seedlings. Poison bait: 90% trichlorfon crystal 100 ~ 150g is added with appropriate amount of water to make a liquid medicine, and then 6 kg of fried rice bran or wheat bran is added to make poison bait, and 3 kg is used every 667 meters, and it is sprinkled on the ridge of crops in the evening to induce poison. Spraying: spraying 90% trichlorfon crystal 1000 times solution 1 ~ 2 instar larvae for control. Root irrigation: After the 3rd instar, the larvae were treated with 90% trichlorfon crystals 1000 times or 50% phoxim 1500 times, and each plant was irrigated with 250 ml. (4) Biological control: There are nearly 20 kinds of natural enemies of the cutworm, so attention should be paid to protecting and utilizing their natural enemies, such as parasitic bees and flies, in order to give full play to the control role of natural enemies.