Identification and Control Methods of the Wheat Stem Borer

Scientific name: Lepidoptera, Noctuidae. Also known as wheat moth, stem borer, stem-boring worm, etc. Distributed in winter wheat regions such as Shandong, Hebei, Jiangsu, and Gansu.

Hosts include @#@245@#, barley, etc.

Damage characteristics: young larvae cause damage inside the leaf sheaths; after wheat and barley jointing, the larvae damage the young leaves, causing leaf curling, stunting, dead hearts, or forming damaged plants, with each larva damaging 2-3 plants. The larvae bore into the base of the first stem node, causing white heads. It is an important pest of wheat and barley in China.

Morphological characteristics: adult body length 5.9-7.9 mm, wingspan 13.5 mm, the whole body densely covered with coarse scales, the top of the head densely covered with grayish-yellow long hairs, antennae filiform, forewings rectangular, grayish-brown, with grayish-brown fine hairs on the outer margin, hindwings slightly wider than the forewings, with white sword-shaped spots along the front margin, and grayish-white fringe hairs on the outer and hind margins. Egg length 1 mm, oblong-oval. Mature larva body length 10.5-15.2 mm, slender and cylindrical, white when young, later yellowish-white, with black spots around the spiracles of the prothorax and abdominal segments 1-8, and one black spot each on the mesothorax and metathorax, with 4 small black dots arranged transversely on the dorsum of the 10th abdominal segment. Pupa length 7-10 mm, spindle-shaped, initially yellowish-white, later turning yellowish-brown.

Life habits: In Shandong and Hebei, 1 generation occurs per year, overwintering as young larvae in the young leaves of wheat; after wheat turns green the following year, damage begins; in mid-to-late May, after the larvae mature, they pupate in the leaf sheath of the wheat flag leaf, and a few pupate in the second leaf sheath. The pupal stage lasts about 20 days. Generally from late May to early June, when wheat enters the maturity stage, adults begin to emerge; adult emergence is favored on sunny mornings, and the emergence period lasts about 10 days. Adults are active fliers, most active from 11:00 to 12:00, and stop activity when the temperature is below 20°C; after emergence and a period of activity, they hide under eaves, in wall cracks, and bark crevices to oversummer, and lay eggs in autumn.

Control methods: (1) During the adult emergence period, hang sacks or other wrinkled objects under the eaves at intervals of 2-3 m to attract them to enter, then collect and dispose of them the next morning. (2) In early to mid-April, when larvae crawl out to be active or move between plants to cause damage, spray 2.5% trichlorfon powder or 1% 1605 powder, 1.5-2 kg per 667 sq m. If necessary, spray 90% crystalline trichlorfon at 1000 times dilution, or 80% dichlorvos emulsifiable concentrate at 1500 times dilution, or 50% phoxim emulsifiable concentrate at 1500-2000 times dilution.