Attention should be paid to the control of chestnut gall wasp this year.

Chestnut gall wasp, also known as chestnut tumor wasp, is the main pest that harms Chinese chestnut, which occurs almost every year in Chinese chestnut producing areas, but it is particularly serious this year. The injured rate of big trees, especially old barren trees that can not be pruned, is up to 100%. It is urgent to control chestnut gall wasp.

The chestnut gall wasp occurs one generation a year and overwinters as the first instar larvae in the killed chestnut buds. In Yanshan mountain area, the overwintering larvae began to feed and grew rapidly in the middle of April, and formed galls at the beginning of May. The gall tumors were mostly at the top of the new branches or the main veins and petioles of the leaves, and the feeding activities were generally about 50 days. The pupae began to age in the middle of May, the peak period was in early June, the pupation ended in early July, and the pupation period was about 15 days. The adult Eclosion period is from the first ten days of June to the middle of July, and the peak period is from the end of June to the beginning of July. the adult does not produce gall after Eclosion, stays in the gall tumor for about 11 days, and falls off the gall from the middle of June to the end of July. the peak period of gall removal is in the first ten days of July. the average life span of adults outside the gall is 3.1 days, the longest is 5.5 days, the flying ability of adults is not strong, they mostly crawl between branches and leaves, move during the day, and perch on the back of leaves at night. Adults can lay eggs after gall, laying 2-4 eggs each time, each female can lay about 200 eggs, and the spawning period is about 30 days. The eggs began to hatch in mid-July, all hatched in early September, and the young larvae began to overwintering in early October.

Prevention and treatment: cut off the gall tumor in time. Before the emergence of adults, combined with pruning to remove gall branches can not only improve the ventilation and light transmission of the crown, but also reduce the source of insects. In winter, all the dormant buds of the annual branches will be cut off, and the fruit can be restored after one year, and the big branches can also be cut off to germinate new branches and rejuvenate the tree. For chestnut trees with serious damage and sharp decline in fruit, short-cut renewal can be carried out. In the gall peak period of adult chestnut gall wasp in early July, the canopy was sprayed with 1000 times of dichlorvos or 1000 times of deltamethrin, once every 7 to 10 days, twice in succession.