Answer: Plutella xylostella, Plutella xylostella, commonly known as hanging wireworms, hanged ghosts, two tips, dishes, etc., are important pests on vegetables. The worm mainly harms cabbage, cabbage, cauliflower, rape and other cruciferous crops. The larvae fed on the leaves and left only the epidermis to form a transparent plaque. The 3rd to 4th instar larvae could eat the leaves into holes, and when severe, the whole leaves were eaten into a net shape.
First, the morphological characteristics
Adult grayish-brown, small individuals, body length 6 to 7 mm, the trailing edge of the fore wing was yellow and white with three twists and turns, when the two wings are closed, three successive diamond-shaped spots. The fore wings are long and curled up like chicken tails. Egg oval, flat, about 0.3 mm long, yellow-green.
Second, living habits
Plutella xylostella occurs in our province for 3 to 4 generations a year, and it is wintering under weeds or leaves of various vegetables. Adults lively, often active during the day, life span 11 to 28 days.
Third, control methods
1. Agricultural control. Rational distribution of crops to avoid continuous cropping of cruciferous vegetables in small areas; to strengthen field management, remove field cruciferous wild vegetables, weeds, and stubble leaves from stubbles in order to reduce the source of insects.
2. Chemical control. The key to drug control is to master the best time of application, that is, to apply the drug before the larval hatching to the second instar. The commonly used agents are: 1.8% of Insect C emulsifiable concentrate 3000 times, or 5% of Frigid suspension 3000 times, or of 1% Emamectin formate 4000 times, or 10% of Pteridone Suspension Agent 1500 times, or 25% diflubenzuron No. 3 500 times, or BT, wotoxin, BT + indoxacarb and other biological agents. Focus on spraying the heart and leaves, and pay attention to the alternate use of medicines.
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The former is a kind of main raw material of cosmetics, which occupies a large proportion in the formula of cosmetics, and is the substance that plays the main function in cosmetics. The latter are responsible for forming, stabilizing or giving color, fragrance and other properties of cosmetics, which are used in small amounts in cosmetic formulations but are extremely important. Cosmetics are chemical mixtures made from natural, synthetic or extracted substances with different functions, which are processed by heating, stirring and emulsifying.
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