Blackberry gall wasp

The blackberry gall wasp (Diastrophus turgidus) belongs to the order Hymenoptera and the family Cynipidae. This insect is primarily known for inducing the development of woody, irregular galls on the canes of various Rubus species, acting as a specialized plant pest.

The host range is largely confined to wild and cultivated blackberries. Adult females utilize their ovipositors to insert eggs into the soft tissues of young canes. The secretion injected during this process triggers the plant to form a gall, which serves as both a food source and a protective chamber for the developing larvae.

The life cycle involves a single generation per year. Larvae develop within the gall throughout the summer and autumn months. By late fall, they are typically mature and remain inside the gall structures to overwinter. Emergence of the adult wasps occurs in the following spring, at which point the cycle begins anew.

Damage caused by this pest is primarily physiological and structural. Large galls disrupt the translocation of water and nutrients within the cane, often leading to stunted growth, reduced berry yield, or even the death of the distal parts of the infested cane above the gall site.

Control strategies rely heavily on sanitation. Growers should monitor plantations for gall formations and prune infested canes well below the gall level during the dormant season. Pruned material must be destroyed by burning to prevent adult emergence. Chemical control is limited to precise timing during the adult emergence phase.