The scientific name of this insect is Nymphula vittalis (Bremer), which belongs to the family Crambidae, not Acrididae. It is commonly known as the rice strainer or rice leaf roller. This species is widely distributed across China, ranging from the northern parts of Heilongjiang and Inner Mongolia, southward to Taiwan, Guangdong, Guangxi, Yunnan, and extending eastward along the border, westward to Ningxia, Gansu, Sichuan, and Yunnan.
The primary host plants include rice, as well as other grasses such as Aunt Mai and various weeds. This pest poses a significant threat to rice crops, especially during its larval stage.
The larvae are particularly damaging as they roll leaves into cylindrical tubes, hiding within them while feeding on the inner tissues. They often reside in water or near the water surface, causing damage to both leaves and roots of the rice plants.
Morphologically, the adult moth has a body length of approximately 5 mm and a wingspan of about 19 mm. The head and thorax are yellowish-white, while the abdomen is light yellow with dark brown scales at the end of each segment. The forewings are yellow with two white stripes running parallel to the outer edge. The outer stripe is thin, while the inner one is thick and bends toward the wing’s trailing edge. A white stripe runs through the middle chamber, and there is a dark brown spot on the front edge. The middle chamber is small, with two black spots and a slash mark below it. The edges of the white stripes are bordered by dark brown lines with white hairs. The hind wings have dark brown spots at the base, with horizontal dark brown lines, wide yellow lines on the outer edge, and brown lines on either side. The outer edge is yellow, with black lines inside and outside, and a black line on the outer edge. These lines connect to the outer horizontal line at the corners. Both wings have gray hair on their underside.
The eggs are elongated, resembling lemons, with a pointed tip and a flat bottom, and have longitudinal grooves on the surface. The larvae grow up to 15 mm long, are flat and light gray in color, with a light brown head marked by dark brown patterns. The first segment of the thorax is notably large, light brown, with an oval ring pattern and long claws on the chest. The pupa measures about 8 mm, pale yellow, and has 2–4 spiracles on the abdomen.
This species typically completes one generation per year, with adults emerging in July. The larvae construct nests using rice leaves and can be found on the soil surface of paddy fields or floating on water, where they feed on roots and leaves. Transgenic rice varieties may also be affected. After maturing, the stems become weak and easily broken. In Ningxia, the population peaks in mid-to-late July, with females laying 30–50 eggs on the water surface.
For control, black light traps can be used to attract and kill adult moths. Regular monitoring is essential; once detected, larvae should be removed promptly. Grass at drainage outlets should be blocked to prevent spread, and 2.5% trichlorfon powder can be applied effectively at a rate of 2.0 kg per 667 m².
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