Detailed Explanation of Key Points on Fall Webworm Control Techniques
The fall webworm is a worldwide quarantine pest, also known as the American ermine moth, autumn webworm, autumn tent moth, etc. It is an insect of the genus Hyphantria in the family Erebidae, order Lepidoptera. It mainly damages fruit trees and ornamental trees, especially broadleaf trees, causing serious harm to garden trees, economic forests, and farmland shelterbelts. It has been listed among China's first batch of invasive alien species. Let's take a look at fall webworm control techniques below!
Morphological Characteristics
Freshly laid eggs of the fall webworm are pale yellow-green or light green, later turning grayish-green, and grayish-brown before hatching. Mature larvae are 28 to 35 mm long, with a black, glossy head. The body is yellow-green to grayish-black. Adults are white, 13 to 15 mm long, with dark brown compound eyes. The dorsal side of the thorax is densely covered with white fuzz. Male adults have black, pectinate antennae, while female adults have brown, serrate antennae. The wings are usually pure white.
Growth Habits
The fall webworm is currently distributed in Liaoning, Hebei, Shandong, Beijing, Tianjin, Shaanxi, Henan, Jilin, Jiangsu, Anhui, Hubei and other places. In Liaoning and other places, it reproduces 2 generations per year. In recent years, observations in Shandong Province show it can reproduce three generations per year. It overwinters as pupae under tree bark or in fallen leaves and litter on the ground. After hatching, larvae spin silk webs and gather in the webs to feed on leaves. After the leaves are eaten up, the larvae move to another part of the branches and tender shoots to weave a new web.
Damage Characteristics
The fall webworm can damage more than 200 species of plants, including fruit trees, forest trees, crops and wild plants. In areas with dense orchards, as well as scenic spots and tree-lined avenues, when outbreaks are severe, it can eat all the leaves of a whole plant, causing some branches or even the entire tree to die. It seriously threatens sericulture, the forest and fruit industry, and urban landscaping, causing astonishing losses. In addition, infested trees become weak in growth, are prone to attack by other pests and diseases, and have reduced cold resistance and stress resistance. The larvae prefer to feed on mulberry leaves, posing a threat to sericulture.
Control Techniques
1. Strengthen quarantine: Nursery stock from epidemic areas is prohibited from being shipped out without quarantine or treatment. Active control should be carried out within epidemic areas to effectively curb the spread of the epidemic.
2. Manual control: Before larvae reach the 3rd instar, manually cut off the webs when they are found and dispose of them centrally. If the larvae have already dispersed, before the larvae descend from the trees to pupate, use the method of binding grass around tree trunks to attract and collect the larvae that descend to pupate, and arrange designated personnel to handle them centrally on a regular basis.
3. Trapping and killing adults: Use fall webworm sex pheromone lures or environmentally friendly insect taxis-based traps to trap and kill adults. During the adult occurrence period, place the lure core into the trap and hang the trap in the forest to directly trap and kill male adults, block mating of the pest, reduce the reproduction rate, and achieve the purpose of eliminating the pest.
4. Chemical pesticides: During the larval damage period, achieve early detection and early control. If there is larval damage, inspect the area under jurisdiction and control it promptly. For pesticides, biological control is preferred: 0.12 propylene glycol alginate (Zaogai Sha), 2.5% lambda-cyhalothrin microemulsion sprayed at 1500 times dilution, Bt emulsion sprayed at 400 times dilution, and 2.5% beta-cypermethrin emulsifiable concentrate at 1500 times dilution can all effectively control the damage of this pest.
5. Biological control: Chouioia cunea is a newly discovered species native to China, yet it has become a natural enemy of the fall webworm. This small wasp can find fall webworms that pupate in various hidden places and lay eggs to parasitize them. This efficient, economical, and pollution-free biological control research and technical achievement has passed appraisal and is being promoted and used on a large scale in epidemic areas.