Table 7-6: Main Pests of Larix principis-rupprechtii in the Mengbian Forestry Bureau Pest Name Chemical Conversion Rate (%) Feathering Rate (%) Sex Ratio (Male to Female) Egg Production (grain) Egg Loss Rate (%) Hatching Rate (%) Overwintering Larvae Loss Rate (%) Number of Juvenile Larvae (per autumn tuft, head, grain) Larch Caterpillar 83 54 1:0.8 300 15 80 35 2 to 4 instar larvae: 0.65/1 (larvae) Larch 81.5 1:1.3 220 6 89 65.2 rods/head (pupa) Larix gmelinii 85 95 1:0.9 32 90 12.3/1 (preliminary) Larix principis 15 0.85 3rd instar larvae / 1 larva Gypsy Moth 600 30 50 0.35 1st instar larvae/1 (egg) Larch Cone Flower Fly 88 51 1:0.8 36 10 80 7.34 1st instar larvae/1 head (pupa) Note: Data collected from system monitoring over the past 10 years. Section 7-7: Classification of Major Pests of Larix principis-rupprechtii in the Mengbian Forestry Bureau Insect Species Insect Unit Level of Danger Forest Age + ++ +++ Larch Caterpillar 3 to 4 instar larvae Article/Strain 5 to 20 21 to 40 40 or more 5 to 10 years 10-30 31~50 above 50 11 to 20 years 20 to 40 41 to 70 More than 70 20 years or more Larch 1st instar larva Article/Strain 400 to 1200 1201 to 3000 More than 3000 15 to 20 years 700 to 1700 1701~3500 3500 or more 21 to 30 years Larix gmelinii 1st instar larva Article/Strain 700 to 1200 1201 to 2500 More than 2500 15 to 20 years 100 to 1500 1501 to 3000 More than 3000 21 to 30 years Larix principis larva Head / 100cm extension sticks 10 to 20 21 to 40 40 or more Gypsy moth 1st instar larva Article/Strain 20 to 40 41 to 70 More than 70 5 to 15 years 30～60 61 to 100 More than 100 16-25 years Larch cone flower fly 1st instar larva Article/Strain 30 to 150 151～300 More than 300 About 15 years Note: The criteria for hazard levels are as follows: 1. Leaf-feeding pests: 1/3 needle damage is light (+), 1/3 to 2/3 is moderate (++), and 2/3 or more is severe (+++). 2. Seed pests: Damage rate below 10% is light (+), 11–20% is moderate (++), and above 20% is severe (+++). Part III: Main Rodents of Larix principis-rupprechtii Rat poisoning is one of the four major forest pests. Among rodents, rats are the most common. According to data, there are over 2,800 rodent species on Earth, with more than 180 in China. However, in the Mengbian Forestry Bureau of Hebei Province, the main rodent species affecting Larix principis-rupprechtii is the brown-backed vole. This section focuses on the rat. First, Clethrionomys rufocanus sunderall Common name: Red-haired mouse, mountain mouse. 1. Taxonomic classification: Rodentia, Muridae, Myomorpha, Cricetidae, Microtinae, genus Clethrionomys. 2. Distribution: Heilongjiang, Jilin, Liaoning, Inner Mongolia, Hebei, Shaanxi, Gansu, Sichuan, Hubei, Jiangxi, Xinjiang. 3. Physical characteristics: Body length 85–115 mm (average 97 mm), tail length 26–36 mm (average 30.7 mm), about 1/3 of body length. Ears short, average 12.5 mm. Eyes round and black. Limbs small. Back fur is red-brown, base gray-black. Side fur is light gray, belly fur is gray. Tail fur short, back is gray-black, belly is gray-white. Skull: Thick and short, with a concave groove in the center of the eye leading to the frontal bone. Long skull, not large cheekbones, slightly thick. Teeth: Large teeth. M1 and M2 have five closed triangles, M3 has four. Last tooth blade often connects with the front triangle, slightly protruding backward. Each side has three protrusions, distinguishable from the red-back plane. 4. Living habits (1) Habitat: After logging in the original broad-leaved secondary forest, the area is now covered by artificial coniferous and broad-leaved young forests. During peak population years, they are found in mountains, slopes, and hills. In lower years, they live in dense weed areas, bushes, wild roses, and flat hazels. (2) Burrow structure: Built under roots, fallen logs, cut roots, shrubs, grasses, and leaf litter. Depth 5–10 cm, width 30 cm, with two or more chambers connected by runways. In winter, holes appear in the snow with crisscross patterns. (3) Feeding behavior and damage: Rats have seasonal diets, preferring green plant parts in summer (young stems, leaves). After spring thaw and fall, they eat young leaves and underground stems. In winter, they feed on seeds and bark, mainly harming larch, pine, and hawthorn trees, causing seedling death or stunted growth. Young trees under 10 years old suffer the most. Trees between 10–15 years are less affected, while those over 15 rarely die. Damage to larch and pine saplings occurs from November to February, mostly at night and early morning. Mild damage strips the base, direction southeast. Moderate to heavy damage rings the trunk, 4–10 cm wide, sometimes over 15 cm. Peeling marks help distinguish rodent damage from livestock. 5. Population characteristics: In the Mengbian area, rats start breeding in April–May when Pulsatilla flowers and Acanthopanax leaves emerge. Breeding season is June–August, with 2–4 offspring per year, averaging 5–6. Lifespan is about 1.5 years. Breeding stops in October. Rat populations fluctuate yearly, generally peaking every three years, with two-year intervals. Population cycles are linked to forest seed availability. In the second year after dominant tree harvests, rat numbers surge into peak years. 6. Feeding observations: Young rats avoid light and heat. Under full light, they die within 3 days even with food. Under shade, they survive normally. Adults prefer high-water-content foods like fruits, berries, vegetables, and dry grains like cornmeal when water is scarce. They can grow on fresh straw like Artemisia ordosica without water. 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