Insect pests and control methods of walnut leaf borer, Chilo suppressalis

   1. Distribution and damage symptoms are the main leaf-eating pests of walnut, distributed in North China, Northwest and Central-South China. The larvae bite on the walnut leaves and can eat up the whole tree leaves when they occur seriously.

   2, morphological characteristics and living habits belong to Lepidoptera, Pyralidae, also known as wood armyworm, Chilo suppressalis.

The adult    (1) has a body length of 14 mm and a wingspan of 35 mm and 50 mm, all of which are yellowish brown. The front wing is dark, the rear wing is grayish brown, the closer to the outer edge, the darker the color.

   (2) is ovoid and densely arranged in the shape of fish fish.

   (3) the mature larvae are 20mm long, black and shiny in the head, black in the dorsal plate of the forechest, 6 yellow-white spots on the front edge, wide line in the back, apricot yellow, yellow-white spots in each segment of the body, yellow-brown on the ventral surface of the abdomen and a small amount of short hairs.

   (4) pupa is about 16 mm long, dark brown to black.

   (5) cocoon is dark brown, flat-oval, about 20 mm long and 10 mm wide.

There is one generation of    every year, and the occurrence period of adults is from late June to early August. The eggs lay on the leaves and hatched in the first ten days of July, and the peak period was from the end of July to the beginning of August. The larvae live in groups, spin silk and form a net on the leaf surface, and roll the leaves together into a tube shape, in which the larvae do harm, and discharge the feces inside, and finally form a mass as the insect body grows. The larvae were scattered after the 4th instar. The larvae feed, move and transfer at night, lie still in the injured leaves during the day, and overwinter as mature larvae in August and September.

   3. Prevention and control methods

  ① hunted and killed artificially. Making use of the characteristics that the larvae live in groups when they are harmful to the leaves, the insect bags can be removed, burned centrally, and killed.

  ② dug up cocoons. Cocoons are generally concentrated in the soft soil next to the roots and can be removed and burned before freezing in autumn or after thawing in spring.

Chemical control of   ③. In mid-late July, in the early stage of larval damage, 25% kungfu EC was sprayed with 1000 times, or 40% toxic cicada EC 800 times, or 40% dimethoate EC 2000 times, or 25% carbaryl wettable powder 500 times 800 times.