Inchworm //
Chǐ huò, the larvae of the ruler moth. It belongs to the arthropods, insects, lepidoptera, and insect larvae of the family Ulmus. The body of the inchworm is slender, flexing and stretching like an arch bridge when moving, and when resting, the body can be obliquely straightened like a branch. Totally perverted. Adults have large wings, slender bodies with short hairs, and filamentous or pinnate antennae, called "ulnar moths".
<h1 class="pgc-h-arrow-right" >01. Hazard characteristics</h1>
The larvae that hatch into the shell are scattered with the wind on the nearby leaves, mostly eating the leaf flesh on the back of the leaf near the leaf tip, leaving only the epidermis, and when seriously damaged, the leaf tip is reddish brown, dry, like a fire. The older larvae, the new and old leaves, feed on them, leaving only some main veins. In severe cases, the leaves of the whole tree are almost unreserved, resembling a broomstick.
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Occurs 3-4 generations a year, and pupae overwinter in the soil. Adults appear in mid-to-late April, with eggs produced on the front of the leaf. There are larvae from early May to late September, with overlapping generations. The larvae disperse after 3 instars, are frightened by suffix silk drooping, and after September, the tree pupae overwinter.
After 5 years of age, the larvae appear purple on the back of the body to indicate that the larvae have entered the old ripe. After aging, they lose the ability to spit silk, and mostly climb down the trunk or fall to the ground during the day to pupate in the soil. Most of the pupal sites are located within the vertical projection range of the canopy, with the southeast side of the canopy being the most.
Under the condition of soft soil, most of the larvae enter the soil at a depth of 2 to 5 cm, and a few 12 cm. Urban street tree larvae mostly pupate under hedges and in floating soil at the base of the wall. When there is no suitable pupal site, it can also be pupated on the bare ground, but the survival rate is very low.
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1. The speed of pupal feathering is fast
Suitable soil and climatic conditions promote large numbers of pupae to feather into adult insects. When the ground temperature at 3 to 10 cm below the local surface is about 0 °C, the overwintering pupae of the spring inchworm begin to emerge and feather, and in the spring year when the temperature rises rapidly, the amount of feathering unearthed in 10 days can exceed 70%.
2. High egg hatching rate
Biological characteristics determine the likelihood of outbreaks. It is characterized by polyphagia, overeating, sagging silk, and high reproductive survival rate. Adults in normal years will mate and lay eggs after 1 week of feathering, a female adult can lay about 100 eggs, under the right temperature conditions, 15 to 30 days can hatch larvae and the survival rate is high.
3. The number of host trees has increased
In recent years, with the implementation of forestry ecological engineering projects and various forestry policies, the planting area of the main tree species such as apples, pears, walnuts and poplars has increased significantly, creating good living conditions for the survival, occurrence and reproduction of spring inchworms.
4. The timing of prevention and control is not accurate
Spring inchworm occurs 1 generation a year, the occurrence time is early, the time is short, the hatching larvae hatch concentrate on the small body, the young larvae harm the young shoots, buds, small amount of food, not easy to be found, once the upper tree is dispersed to the upper part of the canopy, it misses the best time for prevention and control, the tree is high and dense, and the control is difficult.
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A. Agricultural prevention and control:
1. Loosen the soil to kill pupae, and seize november to February, mid-to-late May, mid-July and late August to early September every year. A total of 4 times, dig pupae in loose soil within 60 cm around the trunk (soil depth 1 to 300 meters), especially the first and second times, is a good time to reduce the source of insects.
2. Trap insects to kill pupae. Before the mature larvae are pupated into the soil, a plastic film can be laid around the trunk (radius of about 60 cm) on top of the loose soil layer with moderate humidity (6 to 9 cm thick) to create a loose and wet soil environment for the larvae pupae, and then concentrate on annihilating it.
3. Artificial culling of moths. Master the peak period of feathering of moths in each generation (mid-March, early June, late July and early August, mid-to-late September), and before the female moths lay eggs, go to the protective forest around the citrus grove every morning or afternoon to beat the moths with branches.
4. Combined with field management to remove egg mass and burn it centrally. Adults mostly lay eggs in the bark cracks of the shelterbelt or on the trunks and backs of citrus trunks and leaves, and the egg blocks are covered with yellow-brown villi and are easy to find, and if necessary, special personnel are arranged to find them and burn them intensively.
5. Light the lamp to lure the moth. In the adult bloom period, a 40-watt black light lamp is set up for every 30 acres of garden to lure the moth.
2. Biological control
Use of natural enemies: No matter how cunning the inchworm is, it also has natural enemies, such as birds, parasitic bees, ants, etc. are its natural enemies. In places where the density of insect populations is relatively small and the harm is light, try to control the practicality of chemical agents and protect all kinds of natural enemies to maintain the balance of the ecosystem.
3. Chemical control
It is recommended to use [indateran + lice mite urea] or [Kang Huan], the control effect is good.