LEPIDOPTERA How does LEPIDOPTERA cause harm?

Celebes, male, 8 ~ 9 mm in body length and 20 ~ 22 mm in wing spread; The female insect is 9 ~ 1 1mm long and its wings are 24 ~ 26mm long. The front wing is gray-brown, with a spiral ring pattern in the center. There are three obvious scale protrusions on the ring, one near the center is gray-white, and the other two are brown. There are also three obvious brown scales near the hip angle. The hind wings are grayish white. Eggs, buns-shaped, about 0.25 mm in diameter and length, are light yellow. There is a small circular depression in the center of the top. Larvae, mature larval body length 14 ~ 22 mm, yellow. There is a black spot on the side of the second to sixth abdominal segments, which becomes two black spots in the later stage; There are two gray longitudinal stripes on the side of the abdomen. Pupa, ovoid, 8.5 ~ 1 1 mm long, taupe. There are a row of longitudinal ridges on the front and back of the abdomen. Silkworm cocoon, length 15 ~ 20mm, oval (Figure 3-20).

Figure 3-20 Leptospira Noctuidae

1 .adult 2. Egg 3. Larva 4. Pupa 5. Cocoon Wu Jianfen According to Wu Jianfen's research (1984), Lepidoptera is distributed in Hubei, Jiangsu, Zhejiang, Fujian, Guangdong, Sichuan and other provinces in China. The hosts are chestnut, pear, guava, Lagerstroemia speciosa, mango, loquat and other plants.

Spodoptera exigua has 7-8 generations in Guangzhou 1 year, and the largest number occurs from April to 10. Adults move at night and lay eggs. Oval, 30 ~ 100 grains per grain, produced on leaf surface. The egg period is 6 ~ 10 days. The hatching rate is generally around 88%. Larvae are very clustered. Except for the last larva which is slightly dispersed, larvae hatched in the same egg block always feed in groups. 5th instar larva. The larvae eat 4747 square millimeters of leaves in their lifetime, accounting for 0.5% of the first instar, 2. 1% of the second instar, 7.6% of the third instar, 3. 1% of the fourth instar and 58.8% of the fifth instar. The larval stage is 65438 03.5 ~ 65438 09.0 days. Under the condition of daily average temperature of 26℃, the development duration of1~ 4th instar larvae is 3 days, and that of 5th instar larvae is 3.5 ~ 4.5 days. 1~ 4th instar larvae only feed on the epidermis and mesophyll on the back of leaves, while 5th instar larvae eat leaves into holes and nicks, or mesophyll is light, leaving only veins. When the larvae mature, they cocoon and pupate on the ground or at the base of the trunk. The pupal stage is 8.0 ~ 12.5 days. The life span of adults is more than 10 day, and the prophase of oviposition is usually 4 ~ 5 days. It takes 34.5 ~ 45.0 days to complete a generation.

Control method: (1) Manual control, generally mild chestnut orchard, using the habit of overgrown larvae, cut off insect branches and leaves when larvae occur, and concentrate on treatment. (2) Chemical control: In the chestnut orchard with serious occurrence, spraying 20% fenvalerate emulsifiable concentrate or 2.5% deltamethrin emulsifiable concentrate 4000 times, 90% trichlorfon crystals 2000 times and 80% dichlorvos emulsifiable concentrate 2500 times on the trees during the larval period, the insecticidal effect is over 90%.