Mango leaf gall midge has 8 generations a year. Overwintering with pupae in orchard topsoil 1-3 cm. Every April, overwintering pupae emerge, and after mating, adults lay eggs on new buds and leaves, and the eggs are scattered, ranging from several to hundreds per leaf. After hatching, the larvae directly invade the mesophyll from the bottom of the eggshell, and the damaged parts first see pink-brown spots, surrounded by yellow-green and water-stained halo spots. With the development of the larva, the leaf tissue of the injured part grows due to stimulation, and gradually bulges to both sides, gradually forming a scab with a diameter of 2-3 mm, one worm and one scab. Larvae never move until they are mature. When the larvae in the galls are mature, they fall off the holes and pupate, resulting in perforation, dryness and even defoliation. Summer and autumn shoots suffer the most throughout the year. Larvae are afraid of drought or strong sunlight. If they can't find wet soil for 2-3 hours after landing, they can't pupate and die under strong light for 2-3 hours. But it can withstand high humidity and live in the basin 15-20 days. Two days after the larvae enter the topsoil, a film is formed in vitro. Then pupate.
Prevention and control methods:
1. In the area where gall midge has been damaged, combined with cultivation management, when clearing the garden in autumn and winter after fruit picking, the branches and leaves of pests and diseases and the shady branches in the inner room are cut off, and the dead leaves in the garden are burned together.
2. Strengthen the water and fertilizer management of mango, so that the bamboo shoot picking period is consistent, which is convenient for centralized control.
3. According to the actual situation of pests, dimethoate, parathion, trichlorfon or diphtheria are selected to kill larvae for l-2 times within 7 days in spring and 5 days in summer and autumn.
4. Before the spring rain in February and March every year, 4-5 kg of 3% phoxim granules and 20 kg of fine sand or mud powder are applied per mu, which are evenly spread on the soil surface in the crown, and then covered with 2 cm thick soil, which can kill the larvae and emerging adults in the soil. Or on the eve of adult emergence, 50% phoxim EC (5 kg per hectare) is used to prepare toxic soil, which is sown in the whole garden, and then cultivated shallowly for 4-6 cm, so that the medicine and soil are mixed and buried shallowly, which plays an important role in reducing the population density of the first generation of insects.