Rose stem sawfly

The Rose stem sawfly (Syrista parreysii) belongs to the order Hymenoptera and the family Tenthredinidae. It is a specialized pest primarily targeting cultivated roses. Unlike many other sawflies that consume leaves, this species specializes in tunneling through the stems of the host plant.

The primary hosts for this insect are various rose species. The larvae bore into the central pith of the stems, creating long, hollow galleries. This damage restricts the transport of nutrients and water, which ultimately leads to the wilting and death of the upper parts of the infested rose stems.

The biology of the pest involves overwintering as larvae inside the stems of the host plants. Pupation occurs within these same tunnels in the spring. Once the adult sawflies emerge, they mate, and females lay eggs under the epidermis of young rose shoots, starting the cycle anew for the next generation.

Damage is characterized by the sudden wilting and subsequent blackening of the shoot tips. Because the larvae remain hidden inside the stem, gardeners often notice the damage only after the shoot has already begun to die back. A thorough inspection usually reveals a small entry hole and the tunnel running down the center of the stem.

Effective control measures require a combined approach. The most critical step is the immediate removal and destruction of all wilting shoots, ensuring the larvae are removed before they can complete their cycle. Additionally, systemic insecticides applied during the adult flight period can provide effective protection by targeting the pest as it feeds.

• Pruning and destroying infested stems
• Monitoring for adult emergence in spring
• Using systemic insecticides to target larvae
• Maintaining vigorous rose health through proper care