Harm and Control of Pig infestation

Pig worm is a kind of bug about five centimeters long, dark green all over the body, fat and chubby, with two red horns on the head, which are the larvae of Bombyx mori (also known as "cabbage worm"). Most of them live on fresh and tender leaves of green vegetables, which are harmful to crops to a certain extent. Let's take a look at the harm and control of pig insects.

Agricultural harm of Pig worms

The pig worm harms the mesophyll of crops. Before the 2nd instar, it can only eat the mesophyll, leaving a transparent epidermis, and after the 3rd instar, it can nibble away the whole leaf. If the insect is light, it only leaves veins, which affects the growth and development of the plant, and results in a decrease in yield. In addition, insect dung pollutes cauliflower bulbs and reduces commodity value. In cabbage, insect population can also cause soft rot.

The occurrence regularity of pigs and insects

The generation of pig infestation varies from place to place every year, with 3-4 generations in Heilongjiang and 4-5 generations in Hebei. Pupae overwinter in autumn on fences, wind barriers, tree trunks and weeds or residual leaves near the host plant. The adults are active during the day, the activity is the highest around noon, and most of the eggs are scattered on the front of the leaves. The main occurrence period of larvae is at the turn of spring and summer and autumn, and the control is not as good as eating up the leaves of the whole field, leaving only the main vein and petiole.

Control methods of Pig infestation

1. Interplanting cruciferous plants such as cabbage or cauliflower in the field of Radix Isatidis to induce adults to lay eggs, then concentrate on killing larvae, and ploughing in time after autumn harvest.

2. Spraying Bacillus thuringiensis 800-1000 times liquid or Pieris rapae granulosis virus with 20 larval units per mu at the initial stage of the occurrence of low-instar larvae has a good control effect on pig insects, and the best spraying time is in the evening.

3. Pay attention to the natural control function of natural enemies and protect natural enemies such as Trichogramma, slightly red cocoon wasp, Phoenix butterfly Jinxiaofeng and so on.

4. Spray with cyanobacteria containing more than 10 billion live spores per gram or Bt wettable powder in the peak period, and the use of chemical pesticides is prohibited.

5. During the peak period of larval occurrence, the larvae can be sprayed 2 times 3 times, such as 1500 times of thiazuron suspension, 1500 times of phoxim EC, 1000 times of phoxim EC, 2000 times of 20% permethrin, 4000 times of 21% cyanohorse EC or 1000 times of trichlorfon crystals.