Hackberry Psyllid

Systematic position: The hackberry psyllid belongs to the order Hemiptera and the family Psyllidae. This genus is specialized, meaning that species within Pachypsylla have evolved a unique symbiotic-like relationship with hackberry trees (genus Celtis), creating complex galls for survival.

Host plants: The primary hosts are species of hackberry trees. These trees are highly valued for their drought tolerance and urban adaptability, which makes the presence of Pachypsylla a significant nuisance for urban foresters and landscape managers who want to preserve the tree's health and appearance.

Biology and life cycle: The life cycle is annual. Adults overwinter in protected areas such as tree bark crevices or dormant buds. In early spring, as leaf growth begins, mating occurs, and eggs are deposited on developing leaves. Once hatched, the nymphs feed on the leaf tissue, triggering the plant to form a protective gall, which serves as both food source and shelter during the insect's development.

Damage and economic impact: The most noticeable sign of infestation is the formation of numerous galls on the leaves. While usually not fatal to a mature, healthy tree, severe infestations can cause premature leaf drop, aesthetic damage, and overall tree stress. In saplings or weakened specimens, heavy psyllid activity may impair growth and increase susceptibility to secondary diseases.

Control measures:

• Monitor leaf development in early spring to identify the onset of psyllid activity.
• Apply systemic insecticides during the early stages of bud break if previous history indicates high pest pressure.
• Promote tree vigor through proper mulching, watering, and fertilization to help the plant recover from foliage loss.
• Encourage natural predators like lacewings and lady beetles that provide biological control within the canopy.