Rice chinensis

This pest primarily damages rice plants, as well as other grasses, legumes, morning glories, mallows, and nightshades. Its feeding activity can significantly impact crop yield and quality.

Injury symptoms include small nicks on leaves caused by nymphs, and in severe infestations, entire leaves may be consumed, leaving only the veins behind. This damage can reduce photosynthetic capacity and weaken the plant.

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. The front wings are green at the front and light brown toward the back. Their heads are wide and oval, with a forward-facing face that is broad and elevated. The sides of the head have nearly parallel edges and longitudinal grooves. The compound eyes are ovoid, and the antennae are filiform. The posterior transverse groove is located behind the middle of the thoracic dorsum. The anterior thoracic plate is conical and slightly inclined backward. The hind legs are longer than the abdomen. Males have a nearly conical tip on their anal plate, with a small triangular projection and no lateral grooves. The female’s abdominal segments have distinct spines, especially on the second and third segments. The ovipositor is long, with large upper and lower petals and fine serrations along the outer edges. Eggs are approximately 3.5 mm long and 1 mm wide, cylindrical, slightly curved, and dark yellow, enclosed in a gelatinous capsule containing 10–100 eggs, usually around 30. Each egg has two longitudinal ridges.

Nymphs go through 5–6 instars, occasionally 7. The first instar is gray-green, with a large, uplifted head and no wing buds. Antennae have 13 segments. The second instar is green, with dark brown vertical stripes appearing on the head and thorax. Antennae have 14–17 segments. The third instar is light green, with obvious dark brown patterns on the head and thorax, and a light line along the dorsal midline. Antennae have 18–19 segments, and wing buds begin to appear. In the fourth instar, the wing buds are triangular, shorter than the first segment of the abdomen, and antennae have 20–22 segments. In the final instar, the wing buds extend beyond the third abdominal segment, with antennae having 23–29 segments.

Life habits vary by region. In Zhejiang and Hunan, there is one generation per year, while in northern areas, there are two generations. Overwintering eggs are laid 1.5–4 cm deep in the soil, near weeds, or under rice plants. In Guangzhou, hatching occurs in late March to early April, while in Nanchang it happens in mid-May, Hubei in late May, Beijing in early June, and Jilin in mid-July. Adults emerge in mid-July in Guangzhou, mid-August in Beijing, and mid-August in Jilin. Second-generation adults typically emerge in September. The adult lifespan ranges from 59 to 113 days, with a pre-laying period of 25–65 days. Egg development takes about 6 months for the first generation and 3–5 months for the second. The nymph stage lasts 42–55 days, and the total life cycle can last up to 80 days. These insects are active in the morning, mate 15–45 days after emerging, and mate multiple times during their lifetime. At night, they are attracted to light. Eggs are laid in the soil, often in furrows, with each female laying 1–3 eggs. Newly hatched nymphs feed on weeds before moving to rice or bean crops at the third instar. Natural predators include frogs, crickets, spiders, and birds.

For prevention, farmers should focus on removing eggs from field edges, ditches, and irrigation channels, where they are commonly laid. Manual removal of eggs can be very effective in reducing infestation levels. Protecting natural predators like frogs can also help control populations. Monitoring the growth of rice plants is essential—especially during the third instar when nymphs begin to move into the fields. When infestations reach 100 individuals per square meter, chemical control is recommended. Pesticides such as 50% phoxim, 50% malathion, or 20% fenvalerate can be applied. Other options include 2.5% kungfructose EC diluted 2000–3000 times, 40% dimethoate at 1000 times dilution, or 2.5% cypermethrin EC at 1000–2000 times. In cases of large-scale infestations, aerial spraying is an effective option. Regular monitoring and timely intervention are key to managing this pest effectively.

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