Wheat leaf moth is also called wheat earworm. Mainly distributed in Inner Mongolia, Gansu, Qinghai and other provinces (autonomous regions). Harmful to larvae. The newly hatched larvae first feed on the flower organ and ovary of the ear. After eating all the food, they move to cause damage. After 2 to 3 instars, they lurk in the seeds to feed. After 4 instars, they move to the flag leaf and spin silk to connect the leaf edges to form a tube. They arrive after sunset. They feed on wheat ears and stop eating before dawn. Each larvae can eat about 30 grains of wheat.
(1) Morphological characteristics
The adult body length is 16 mm, the wingspan is about 42 mm, and the body is dark brown. There is an obvious black sword pattern on the forewing, which is in the shape of a swallow flying below the midrib. The ring pattern and kidney pattern are silver gray with black edges. There are 7 black spots on the outer edge of the forewings and dense hairs; the hind wings are light yellowish brown. The eggs are round, milky white at first, then turn grayish yellow, with chrysanthemum patterns on the egg surface. The larvae are grey-brown in color, with a body length of about 33 mm in the final instar, a light yellow figure-eight stripe on the head, and a white backline. The pupae are yellowish brown or tan, 18 to 21.5 mm long.
(2) Occurrence pattern
One generation per year, with mature larvae overwintering under the topsoil in the field. From the end of April to mid-May of the following year, the larvae make cocoons in the surface soil and pupate, with a pupal period of 45 to 60 days. From mid-June to early July, adults enter their peak emergence period. They hide under wheat plants or grass during the day and fly out at dusk to feed on wheat pollen. Eggs are laid on the inside of the spikelet or on the ovary. The egg period is about 13 days and the larvae are 7 instars. The infestation period of the larvae can last for 60 to 70 days, and the larvae begin to overwinter in the rhizosphere soil of wheat stubble in mid-September.
(3) Prevention and control measures
The first is to trap and kill adults. Using the phototaxis of adults, install frequency vibration insecticidal lamps or black light lamps from early June to late July to trap and kill adults. The second is chemical control. Spray pyrethroid insecticides or 90% crystalline trichlorfon 1000-1500 times before the 4th instar of the larvae, or 1000 times 50% phoxim emulsifiable concentrate, 50 kg of spray solution per 666.7 m2 . Larvae after the 4th instar lurk during the day, and when controlling them, attention should be paid to spraying the above insecticides after sunset.