Control Methods for the Ligustrum Looper Moth Damaging Ornamental Garden Trees
Distribution and Damage The ligustrum looper moth Naxa seriaria Motschulsky, also known as the lilac looper moth, belongs to the order Lepidoptera, family Geometridae. It is distributed throughout Northeast, North, Northwest, Southwest and East China. The larvae damage Syringa reticulata, Syringa pekinensis, Syringa reflexa, Syringa oblata, Syringa wolfii, Syringa oblata var. alba, ligustrum, large-leaved ligustrum, osmanthus, camellia, tea, privet, Manchurian ash and Chinese ash, etc. The larvae gather in groups to feed on leaves and often strip the leaves completely. The larvae have the habit of spinning silk to form webs; in severe cases the webs cover the tree crown, causing tree death and affecting the greening and beautification effect.
Morphological Characteristics The adult body length is about 14 mm, and the wingspan is about 38 mm. The body and wings are white, with a slight gray and metallic luster. There are two rows of black dots on the outer margin of the wings, and large black spots on the surfaces of the forewings and hindwings. The eggs are light yellow and oval. When mature, the larva is about 20 mm long, with a black head capsule and a soil-yellow body bearing irregular black spots. The pupa is light yellow with black dots.
Life Habits In Northeast and North China, 1 generation occurs per year, with larvae overwintering in the soil. Adults begin to emerge in June, and adults are phototactic. The larvae have 8 instars in total. The larvae spin silk to form webs on the tree crown; after the leaves inside the web are eaten clean, they move to cause damage elsewhere, spinning webs first and then feeding. In September, older larvae descend from the trees and enter the soil to overwinter. In East and Southwest China, 2 generations occur per year, with larvae overwintering on branches. In the following spring they continue to cause damage, pupate in May, the first-generation adults emerge in June, and the second-generation adults emerge in August.
Integrated Control
(1) Eliminate the source of the pest When the pest infestation is severe, manually dig for pupae in late autumn or early spring to eliminate the source of the pest.
(2) Trap and kill adults Because the adult occurrence period is long, using black light lamps for trapping and killing is more effective.
(3) Chemical control When infestation is severe, promptly spray 10% Anlubao emulsifiable concentrate or 25% Actara water-dispersible granules at 4000 times dilution for control, to reduce the pest population density and avoid serious damage.