Hackberry bud psyllid

Systematic position. The hackberry bud psyllid (Pachypsylla celtidisgemma) is a member of the order Hemiptera and the family Psyllidae. This insect is highly specialized and is primarily known as a significant pest of various species within the Celtis genus.

Host plants and damage symptoms. The insect specifically targets hackberry trees. The most recognizable symptom of infestation is the development of abnormal, woody growths known as galls, which form directly on the buds during the early spring growth flush.

Biology and life cycle. The life cycle involves egg, nymph (five instars), and adult stages. Adults overwinter in protected areas such as bark crevices. In early spring, females lay eggs on the swelling buds. Upon hatching, the nymphs feed on the plant tissue, inducing the tree to form a protective gall where the nymphs live and mature.

Economic impact. Heavy infestations result in severe bud deformity and stunted growth of the new shoots. While the damage is rarely fatal to mature trees, it significantly degrades the aesthetic value of hackberries used in landscape architecture and urban forestry by causing unsightly twig distortions.

Control measures. Managing this pest is challenging due to the protective nature of the galls. Key strategies include:

• Application of systemic insecticides specifically timed to coincide with egg hatch.
• Pruning and removal of heavily infested twigs to reduce the localized population.
• Promoting overall tree vigor through proper fertilization and watering to help trees recover from heavy feeding pressure.