Rice chinensis

The damage caused by this insect includes feeding on leaves, creating small nicks that can become severe, leading to entire leaves being consumed, leaving only the veins behind. This type of feeding can significantly reduce crop yield and quality.

Morphologically, adult males measure between 15–33 mm in length, while females range from 19–40 mm. They are typically yellow-green or brown-green in color. Their front wings are green at the front and light brown toward the back. The head is wide and oval, with a forward-facing face and distinct longitudinal grooves along the sides. The compound eyes are ovoid, and their antennae are thread-like. The posterior transverse groove is located behind the middle of the thoracic plate. The anterior thoracic plate is conical and slightly tilted backward. The hind legs are long, extending beyond the end of the abdomen. Males have a nearly conical tip on the anal plate, with no lateral grooves and a sharp apex. In females, the second and third abdominal segments have short spines on the back, and the egg-laying flaps are long with large upper and lower petals and finely serrated edges. Eggs are about 3.5 mm long and 1 mm wide, elongated and slightly curved, dark yellow, and enclosed in a gelatinous capsule containing 10–100 eggs, usually around 30. The eggs are arranged in two oblique columns.

Nymphs go through 5–6 instars, occasionally 7. The first instar is gray-green with a large, raised head and no wing buds, having 13 antennal segments. The second instar is green with dark brown vertical stripes appearing on the head and chest, and antennae ranging from 14 to 17 segments. The third instar has a light green body with clear dark brown patterns on the head and chest, and the dorsal midline is light. Antennae have 18–19 segments, and small wing buds begin to appear. By the fourth instar, wing buds are triangular, shorter than the first abdominal segment, with 20–22 antennal segments. In the final instar, the wing buds extend beyond the third abdominal segment, and antennae have 23–29 segments.

Life habits vary by region. In Zhejiang and Hunan, there is one generation per year, while in northern and southern regions, two generations occur annually. Overwintering eggs are laid 1.5–4 cm deep in soil, near field edges, ditches, or in the rhizosphere of weeds and rice plants. In Guangzhou, hatching occurs in late March to early April; in Nanchang, it's mid-May; in Hubei’s Hanchuan, late May to early June; in Beijing, mid-July; and in Gongzhuling, Jilin, mid-July. Second-generation adults emerge in mid-August in most areas, with the second generation emerging in September. Adult lifespan ranges from 59 to 113 days, with a pre-oviposition period of 25–65 days. The egg stage for the first generation lasts about 6 months, while the second generation’s egg stage is 3–5 months. The nymph stage lasts 42–55 days, and the adult stage can last up to 80 days. These insects are active in the morning, mate 15–45 days after emergence, and mate multiple times during their lifetime. They are attracted to light at night and lay eggs in the soil, often near ridges. Each female lays 1–3 eggs. Newly hatched nymphs feed on weeds initially, then move to rice or beans after the third instar. Natural predators include frogs, crickets, spiders, and birds.

For control, farmers should focus on destroying eggs in sprouting rice fields, ditches, and canals. Manual removal of eggs can be effective in areas with heavy infestations. Protecting natural predators like frogs can also help suppress populations. Monitoring for young nymphs in the third instar stage before they move into rice fields is crucial. When infestations reach 100 insects per square meter, spraying is recommended. Pesticides such as 50% phoxim, 50% malathion, or 20% fenvalerate can be used. Dilutions like 2.5% kungfructose EC at 2000–3000 times, 40% dimethoate at 1000 times, or 2.5% cypermethrin EC at 1000–2000 times are effective. In cases of large-scale infestations, aerial spraying may be necessary for efficient control.

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