Small land tiger is one of the most widely distributed and most harmful underground pests in China, with a very mixed diet, mainly using larvae as pests of various crop seedlings. When the harm is serious, it often causes a shortage of seedlings and ridges, resulting in a decrease in production.
Other names: soil silkworm, black silkworm, and root worm, etc
Scientific name: Agrotis ypsilon Rottemberg
Classification: Lepidoptera, Noctiaceae
Hazard characteristics
The main crop of small land tigers is seedlings, and newly hatched larvae often cluster on the heart leaves or on the back of the leaves to feed, biting the leaves into small gaps or meshes. After the 3rd instar larvae, they burrow into the soil and damage, bit off the stem of the seedling near the ground, and often drag the bitten seedling into the hole, and its upper leaves are often exposed outside the hole, causing the whole plant to die, resulting in a lack of seedlings and ridges and even the destruction of seeds.
Small ground tiger larval morphology
Morphological characteristics
1. Adult insects: Adults are 17-23 mm long and have a wingspan of 40-54 mm. All gray-brown. The forewings have two pairs of transverse stripes, pale yellow at the base of the wing, black on the outside, grayish yellow in the middle, and have 1 ring, the kidney stripe is black; the hindwings are off-white, translucent, and light brown around the wings. The female antennae are filamentous. The male antennae are ctenophoric.
Male adults
Female adult morphology
2, larvae: the head is dark brown, there are black brown markings on the side, the body is black brown with a slight yellow, dense black small round process, the abdomen end of the supra plate has a pair of obvious black stripes, the dorsal line, the sub-dorsal line and the valve line are black brown, not very obvious, the valve is long ovate, black.
3. Egg: flat and round, the corolla is divided into three layers, the first layer of chrysanthemum petals, the second layer of rose petals, the third layer of radial diamonds.
Pupal morphology
4. Pupae: 18~24mm long, reddish-brown to dark brown. The base of the 4th to 7th segment of the abdomen has a circle of engravings, and the back is large and dark. The ventral endings are elongated with a pair of shorter, dark brown spines.
Regularity of occurrence
The algebra occurs in different regions of China, and generally 3-4 generations occur every year. Pupae and larvae overwinter in the soil. It was feathered in large quantities from late March to early April of the following year. The first generation of larvae occur the most and are the most harmful. 1-2 instar larvae cluster seedlings top heart young leaves, eat day and night, and begin to disperse after 3 instars, a total of 6 instars. Lurking near the rhizosphere topsoil during the day, it bites the seedlings at night and can drag the broken seedlings into the burrow. Adults are diurnal and nocturnal, have strong chemotacticity, have a strong tendency to the sweet and sour smell of fermentation and wilted poplar branches, and have a strong tendency to black light. Adults begin mating 1 to 2 days after feathering and lay eggs on the 2nd day after mating. The eggs are scattered, mostly in soil blocks and gaps in the ground, sometimes on dry grass stems or stems on the soil surface, and a few on the reverse side of crop leaves. The amount of eggs laid is related to the quality of the supplementary nutrients obtained and the nutrition of the larval stage. More than 1,000 eggs can be laid per female and more than 2,000 eggs are laid.
The life of a small land tiger
Prevention and control methods
1. In the spring, remove weeds on the side of the road, shed edge, ditch edge, etc., eradicate the habitat and spawning site, reduce the wintering base and eliminate the initial eggs and larvae.
2. Before sowing, 4% diazinphos granules can be used to 2-4 kg/mu for burrow application or strip application to prevent and control the harm of small land tigers to seedlings.
3. In the peak period of the occurrence of 1 generation of larvae, it can be used to add a solution of enemy insects such as paulownia leaves, gray cabbage, prickly cabbage, kale, etc., and apply them in piles in the field at night to trap the larvae.
4. Pharmaceutical control, small land tiger 1 to 3 years old larval stage of poor resistance, and exposed to plants or ground, is the best period for spray control. 20% chloranthrodium benzamide suspension 1500 times liquid can be used to spray the seedlings evenly, which can effectively prevent and control the harm of small land tigers.