Control methods of privet inchworm in garden ornamental trees

Distribution and damage of privet inchworm NaxaseriariaMotschulsky, also known as lilac inchworm. It belongs to Lepidoptera, Geometridae. Distributed in Northeast, North China, Northwest, Southwest and East China. The larvae are martyr, Beijing clove, weeping clove, lilac, Liaodong clove, white clove, privet, big leaf privet, sweet-scented osmanthus, camellia, tea, water wax, Fraxinus mandshurica and Fraxinus mandshurica. The larvae gather to feed on the leaves, often nibbling away at the leaves. The larvae have the habit of spinning and netting, and when they are serious, they cover the tree crown, resulting in the death of trees and affecting the effect of greening and beautification.

The morphological characteristics of the adult are about 14 mm in length and 38 mm in wingspan. Body wings white, slightly gray and metallic luster. There are two rows of black spots on the outer edge of the wing, and there are large black spots on the front and rear wings. The egg is yellowish and oval. When mature, the larvae are about 20 mm long, with black head shell, yellow soil and irregular black spots on the body. The pupa is yellowish with black spots.

Living habits occur one generation a year in Northeast and North China, overwintering as larvae in the soil. In June, the adults began to Eclosion, and the adults had phototaxis. The larvae are 8 instar. The larvae spin silk and form a net on the canopy, and when the leaves in the net eat light, they transfer the damage, forming the net first and then feeding. In September, the elder larvae went down to the tree to survive the winter. Two generations a year occur in East and Southwest China, overwintering as larvae on branches. The damage continued in the following spring, pupating in May, Eclosion of the first generation of adults in June, and emergence of the second generation of adults in August.

Integrated prevention and cure

The main results are as follows: (1) when the elimination of insect pests is serious, the pupae are dug manually in late autumn or early spring to eliminate the insect source.

(2) due to the long occurrence period of adults, the effect of trapping and killing adults with black light is better.

(3) when the chemical control is serious, spray 4000 times solution of 10% Anlubao EC or 25% Aktai water dispersible granule in time to reduce the insect population density and avoid causing great harm.