Chongyang wood spotted moth is an insect of the Lepidoptera spotted moth family, which is widely distributed in Henan, Jiangsu, Zhejiang, Hunan, Hubei, Yunnan, Fujian, Guangdong and other provinces in China, and the main harm object is Chongyang wood. In recent years, with the creation of garden cities and forest cities, a large number of heavy yang trees have been planted in the green areas of central and southern China, resulting in serious damage to the heavy yang wood golden spot moth. Its larvae feed on the leaves, and in severe cases, the leaves are eaten up, and only the leaf veins remain, affecting the photosynthesis of the plant and reducing the ornamental value. In order to effectively control the harm of this insect to Chongyang wood, the occurrence and control of Chongyang wood moth are discussed.
Morphological characteristics:
Morphological characteristics
Adults: 17–24 mm in length, 19 mm in average, 47–70 mm in wingspan, 61 mm in average. The head is small, red, and has dark spots. The antennae are black and toothed, and the antennae of the male moth are wider than those of the female. The back of the thorax is brown, and the anterior and posterior center is red. The mid-thorax has a dark brown back with a red front end; there are 2 red markings near the posterior end, or connected in a "U" shape. The forewings are black with blue light at the base of the reverse. The hindwings are also black , with a bluish-green color from the base to the proximal end of the wing ( 3/5 of the wing length ) . The anterior and posterior fins are basal spots red. The second and third midribs of the hindwings are elongated into a caudal horn. The abdomen is red with 5 columns of black spots, which are now gradually smaller, but the females have larger dark spots than the males, so that the 2 columns of black spots on the female ventral surface are combined into 1 column in the first to fifth or sixth segments. The end of the abdomen of the male moth is blunt and concave; the end of the abdomen of the female moth is sharpened, and the ovipositor is exposed to a dark brown color.
Egg: round, slightly flattened, less than 1 mm wide, smooth surface. It is initially milky white, then yellow, and light gray near hatching.
Larvae: the head is often indented, the body is hypertrophied, the surface of the body is covered with thorny protrusions, protruding with anchor spikes, as the larvae grow, the body surface branches become more and more obvious. The larvae are initially pale yellow in color, then fade into a pale yellowish-brown color, with black dotted stripes and spiny protrusions arranged interchangeably. Generally 6-7 years old.
Pupae: Body length 15.5-20 mm, average 17 mm. The pupae are yellow in color and have a slight pink tinge on the abdomen. The 7 knot lines on the back are divided into sections, and the sections are obvious. The old mature larvae form a bun-shaped white silk cocoon when the conditions are suitable, and pupate in the cocoon. When the larvae are not fed enough, underdeveloped or the cocooning conditions are not suitable, they can also be directly pupated into naked pupae without cocooning.
Causes of occurrence:
First, plant quarantine does not play its due role in landscaping, in the process of seedling transportation, can not deal with the emergence of insect source trees in time; second, the planting design is unreasonable, the planting density is too large, which is conducive to the spread of the Heavy Yang Wood Moth; the third is the improper control of the appropriate period of control, the heavy Yang wood is generally tall, the harm is lighter and often not easy to find, when the harm is heavier, the prevention and control period has been missed, and the insect will crawl to a hidden place, bringing difficulties to the comprehensive spray prevention, spray control is generally not easy to be thorough and uneven spraying Fourth, the Chongyang wood moth occurs several generations a year, and there is a phenomenon of generation overlap, which makes it difficult to control; fifth, the use of drugs is unreasonable, and at present, there are more highly toxic pesticides used in the prevention and control process of the Heavy Yang wood moth, and the natural enemies of the insect are also harmful, such as parasitic bees, birds, etc.
Occurrence rules:
The Chongyang wood spotted moth occurs in 4 generations a year in most areas. The insects are not neat and the generational overlap is more obvious. The 1st-4th generation of larvae occur in late May, early to mid-July, late August and mid-November, with the most harmful larvae being the 2nd-3rd generation. In early November, the last generation of adult insects appeared, which is more adaptable to overwintering, mainly in the form of larvae or larva cocoon pupae in bark and wall crevices, rocks, weeds and other places.
After wintering, it hatches from late April to late May, and peaks in early to mid-June for first-generation larvae. The second generation of larvae hatch in mid-July and can eat the whole tree in 3-4 days in early August. The third generation of insects hatches in early to mid-September, especially in late September, and often eats up all the green leaves of the tree, leaving only the leaf veins. The fourth generation of insects occurs in early to mid-January and occurs in relatively small numbers. From late November to December, there are generally no insect pests.
Prevention and control measures:
1. Strengthen phytosanitary. Check the tree body more often to find the insect source tree as soon as possible. When the insect source tree appears, it is treated in time, the larval plant is picked out, and the eggs or larvae are scraped with a sharp tool.
2. Reasonable design. When planning and designing the garden, the growth habit of chongyang wood is fully considered, and the strip and block mixed planting is carried out with other insect-resistant tree species, and the single plant is planted at intervals or the spacing is appropriately increased when the street tree is planted.
3. Protect biological predators. When carrying out chemical control, high-efficiency and low-toxicity pesticides are used to protect natural enemies such as parasitic bees and birds.
4. Strengthen conservation management. In late autumn and early winter, the trunk is whitened to kill the overwintering larvae or eggs; before wintering, the trunk of the tree is gathered before the 4th generation of mature larvae pupate, and the overwintering larvae are cleared in the winter, and the overwintering grass is burned; in the winter, the overwintering pupa cocoons in the middle of the lawn under the stones are removed in time.
5. Rational chemical control. Insecticide sprays are applied in early May to kill hatching larvae and reduce the number of insect sources, and from mid-early June to early August, during the peak of the hazard period, at an interval of about 20 days, spray the insecticide twice to reduce the degree of harm. Insecticides should be selected from high-efficiency, low-toxicity, touch-killing and fumigation-strong pesticide varieties, using 500-800 times liquid and other agents such as Lyen Ping Anruiqing, evenly spraying leaves and trees, and spraying on the surrounding grass, stone crevices and other plants. It can also be sprayed with 1.2% nicotinine emulsion 800-1000 times liquid, or 1% insecticide emulsion 2000-2500 times liquid during the larval stage, or Uranus and other permethrin insecticides.