Control Techniques for the Metarbelid Moth (Arbela) in Litchi Cultivation

The litchi metarbelid moth (Arbela) damages litchi and longan, and also attacks citrus, Acacia confusa, Casuarina equisetifolia and various other fruit trees and forest trees. It bores into branches and trunks to form tunnels, but mainly damages the bark and cortex of branches and trunks, seriously affecting growth. When young trees are damaged, they may die.

Life habits: one generation occurs per year, overwintering as larvae, pupating from mid-March to late April, emerging as adults in April-May, laying eggs from late April to early June, with larvae beginning to appear from May to June. The moths are rarely phototactic, and eggs are mostly laid on branches and trunks more than 10 cm in diameter. The larvae bore into the tree body at branch crotches or wounded areas to form tunnels for dwelling, and at the same time, at the tunnel entrance, along the direction in which they feed on the bark, they spin silk to combine frass and bark debris into a silken tunnel. The tunnel is the place where the larvae dwell and pupate. The larvae come out at night to cause damage, moving beneath the silken tunnel on the branches and trunks, and gnawing and damaging the bark on the outside of the tunnel. The silken tunnel can reach up to 0.6 m in length. The tunnel is about 5 cm deep.

Control methods: 1. Use a syringe to draw dichlorvos emulsifiable concentrate at 1:1 (water) or other organophosphorus pesticide solutions in the same proportion, and inject about 0.5 ml into the tunnel, which can kill the larvae. 2. From June to July, spray diluted carbaryl or pyrethroid solutions on the branches and trunks near the tunnels, which can kill the early-stage larvae on contact. 3. Use bamboo or wooden sticks to plug the tunnels so that the larvae or pupae suffocate to death. A steel wire can also be used to stab them to death.