What are the control methods for the rice water-dropwort grasshopper?
Scientific name Gesonula punctifrons (Stal), belonging to Orthoptera, Acridoidea. It is distributed in Jiangsu, Zhejiang, Jiangxi, Fujian, Guangdong, Guangxi, Taiwan, China, Sichuan, Yunnan and other provinces and regions.
Hosts include rice, taro, lotus root, wild narcissus, sugarcane, corn and other plants.
Damage characteristics: adults and nymphs chew leaves into notches or eat the leaf mesophyll leaving the epidermis; damaged leaves show small purple transverse spots, affecting photosynthesis and hindering plant growth.
Morphological characteristics: female adult body length 19-22 mm, male adult 17-18 mm, body yellow-green. Behind the compound eyes and at the upper end of the lateral lobes of the pronotum there are dark brown longitudinal stripes extending backward to both sides of the mesonotum and metanotum. Forewings yellow-green, hindwing base pale blue, apex slightly smoky. Hind femur yellow-green, lower knee lateral lobe red, tibia pale cyan-blue, base red. Head shorter than pronotum. Frons sloping backward and forming an acute angle with the vertex; frontal ridge with a distinct longitudinal groove. Vertex slightly protruding forward; the width of the vertex between the compound eyes is narrower than or equal to the width of the facial ridge between the antennae. Compound eyes oval. Antennae filiform, reaching or exceeding the posterior margin of the pronotum. Pronotum narrower at the front end, wider at the rear end, median carina weak, cut by 3 transverse sulci, the posterior transverse sulcus located behind the middle;
The anterior margin is nearly straight, and the posterior margin is arc-shaped. Forewings and hindwings well developed, exceeding the apex of the hind femur. The inner side of the hind tibia has 8-9 spines, and the distance between the first and second spines at the apex is longer than the distance between the other spines. Egg length 4-5 mm, elongated cylindrical, pale yellow when newly laid, gradually becoming deep yellow, in egg pods, externally covered with a sac-like gelatinous protective substance. Newly hatched nymphs light green, later gradually becoming yellow-green.
Life habits: one generation per year, and up to 3 generations can occur in Guangdong. It overwinters as adults under dead branches and fallen leaves. It begins activity in late March to early April of the following year, and lays eggs in May and June. Eggs are laid in the middle and lower parts of leaf petioles; the bore hole secretes a yellow-brown glue. Each female lays 8-10 egg pods, each pod containing about 6-18 eggs. The egg stage lasts 20-32 days. Nymphs have 6 instars, and the nymphal period lasts more than 30 days. From October to November they successively enter the overwintering period. Adults are active during the day; when the weather is hot at noon, they mostly fly and jump on leaf surfaces and rarely feed. In fields, the population is relatively large each year from July to early September.
Control methods: (1) During the peak egg-laying period of the taro grasshopper, scrape and kill the unhatched eggs at the egg-laying holes. When the egg holes have become smooth and exude a rusty-brown juice, the eggs have hatched or are close to hatching; as long as the scraping and killing time is grasped accurately, the damage can be reduced. (2) Spray pesticides for control during the peak period of adults and nymphs; for the types of pesticides used, refer to the Chinese rice grasshopper.