What are the characteristics and control methods of the black locust moth?

The black locust moth is commonly known as the black locust bark borer. It mainly damages black locust (Robinia pseudoacacia). Its larvae bore into and feed on the bark of the trunk; the affected areas develop hyperplastic swelling, the bark splits and cracks, the tissue beneath the bark becomes filled with rotting matter, and the bark crevices are strung together with frass; this can weaken the tree and even kill the whole plant.

Adult: female moth body length 7-10 mm, wingspan 17-22 mm, male moth slightly smaller; body grayish white or dark brown, thorax and wing base plates grayish white; forewings grayish white mixed with grayish brown or dark brown scales, with an upright tuft of dark brown scales at the wing base, and 2 oblique rows of scale tufts on the wing surface, several tufts per row; hindwings and abdomen grayish yellow; female moth has a pointed abdominal tip and no scale bundle, male moth has a flat abdominal tip and a scale bundle. Egg: round, initially white, later turning yellow to yellowish brown. Larva: final instar body length about 20 mm, yellowish white, head reddish brown, anterior half of the pronotal shield light brown, posterior half dark brown. Pupa: about 10 mm long, reddish brown. Cocoon: grayish white, nearly cylindrical, rounded at the bottom, flat at the top, with a round cocoon lid.

The black locust moth has 2 generations per year and overwinters as larvae of various instars in thin silken cocoons within tunnels under the bark. In late March of the following year they become active and feed, and mid-May is the peak period of adult emergence. The 1st generation eggs occur from early June to mid-July, larvae appear in mid-June, pupation begins in mid-July, and adults emerge from late July to early September, with the emergence peak in mid-August. In the 2nd generation, eggs occur from early August to mid-September, hatch into larvae in mid-August, and the larvae overwinter successively until late October. Adults rest motionless during the day and mate and lay eggs at night. Eggs are mostly laid at wounds on branches and trunks, and also in bark crevices, in piles, with 4-30 eggs per pile, covered with yellow egg fluff. The egg stage lasts 6-13 days. Newly hatched larvae sneak under the bark and feed on the cortex, boring longitudinal tunnels between the phloem and xylem, using bark crevices as entrance and exit holes, with the openings covered by frass strung together with silk. After repeated damage, the affected areas have overlapping tunnels, hyperplastic swelling of tissues, and splitting and peeling bark. After the larvae mature, they spin cocoons and pupate at the tunnel openings. The pupal stages of the overwintering generation and the 1st generation are 11-23 days and 11-15 days, respectively.

Control methods. Spray the trunk with 50% dichlorvos emulsifiable concentrate at 20 times dilution to control larvae; during the adult occurrence period, apply "741" inserted-tube smoke agent at 0.35 kg per mu to kill adults.