Chestnut (Lachnus tropicalis Van der Goot) is the alias for Chestnut Chestnut and Chestnut Black Chestnut. Distribution is widespread, in addition to damage chestnut, but also damage white lice, paralysis and so on.
Harmful features Adult and nymphs cluster on the shoots, twigs and leaves to suck juice, affect the shoot growth and fruit maturation, often leading to tree weakness, and is one of the important pests of chestnut.
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Morphological characteristics adults: wingless and female, female body length 3 ~ 5 mm, black, body back was dense hair. Abdominal hypertrophy is spherical, winged and parthenocarcases are slightly smaller, black, and pale belly. The wings are narrow and long, with two types of wings: one type with transparent wings and black veins; the other with dark wings, black veins, oblique middle wings of the forewings, two posterior horns, and one transparent spot near the vertex of the leading edge.
Eggs: Long elliptic, about 1.5 mm long, dark brown at first, later black, shiny. The monolayers are densely arranged on the branches at the base of the shade and at the base of the coarse branches.
Nymphs: body shape like wingless orphan female, but the body is smaller, lighter color, mostly yellow-brown, slightly larger after the gradient black, the body is more straight, nearly oval. The winged beak is more developed on the chest and has winged buds.
Life history and habits? Li Dayi can occur in more than 10 generations in 1 year, and the eggs are overwintering in the buds and cracks of chestnut branches. In the late March to early April of the following year, the wintering eggs are hatched as dry mothers, intensively consuming juice in the original branches, and the mature and non-winged parthenogenetic females and reproductive offspring. From the end of April to the middle of May, it reached the peak of reproduction, which was also the most serious period of the year. It also secreted honeydew and polluted the leaves. In the middle and late May of the year, winged beaks began to form, and some of them migrated to the summer host to breed. From January to October, the chestnut trees were replanted to continue the reproduction of the orphaned females. They were often clustered on the fruit stems of the chestnut seedlings. In November, they were born with sex mothers, and then the sex mothers regenerated into females and males. After mating, they laid eggs for the winter. Li Dayi's average temperature is approximately 23°C in 10 days, and the relative humidity is approximately 70%. It is suitable for reproduction. Generally, it takes 7 to 9 days to complete one generation. Temperatures above 25°C, and humidity above 80% gradually decreased. In case of storms, it will cause a lot of death.
Control methods
1. Eradicate overwintering eggs by spraying 50-60 times of oil emulsion before germination in winter or early spring. Or brush into pieces of eggs.
2. Chemical control After the overwintering eggs have hatched before chestnut leaf expansion, choose 10% imidacloprid 2000 times spray, 80% dichlorvos EC 1000 to 1500 times, 2.5% deltamethrin EC or 2O% cypermethrin EC 4000 ~ 500O times liquid and so on. Young trees can be dried with 5 times liquid dimethoate, and then wrapped with plastic film, the effect is good, but will not kill the natural enemies.
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