Laurel sucker

The laurel sucker (Trioza alacris) is a sap-sucking insect belonging to the order Hemiptera and the family Triozidae. It is a major pest specifically targeting Laurus nobilis (bay laurel), frequently causing aesthetic and physiological damage to the ornamental foliage of these trees.

Regarding its biology, the adult insects overwinter in sheltered locations, emerging in early spring to lay eggs on the undersides of young, developing leaves. Upon hatching, the nymphs begin to feed by inserting their piercing-sucking mouthparts into the leaf tissue, which triggers a morphological change in the leaf structure.

Damage is characterized by severe leaf curling and the formation of pseudo-galls. The leaf margins roll downward and inward, creating a protected micro-environment for the nymphs to feed. These leaves often turn yellow, become brittle, and can eventually die or drop off, leading to sparse foliage on heavily infested shrubs.

The economic and aesthetic impact is significant, as the curled and yellowed leaves make the plant unattractive. Persistent infestations can stunt plant growth and weaken the tree, making it more susceptible to environmental stressors or secondary opportunistic infections from fungi or bacteria.

• Pruning and destroying infested foliage during the early stages of the attack.
• Application of systemic insecticides approved for ornamental use in early spring.
• Monitoring adult activity using yellow sticky traps to time the treatments correctly.
• Encouraging natural predators, such as ladybirds and lacewings, in the garden ecosystem.

Effective management requires vigilance during the peak growth period of the bay laurel. By targeting the first generation of nymphs before the leaf margins become tightly rolled, gardeners can prevent the most severe damage and maintain the structural integrity of the plant throughout the growing season.