Rose stem gall midge

The rose stem gall midge (Resseliella oculiperda) belongs to the order Diptera and the family Cecidomyiidae. It is a highly specialized pest that primarily affects rose nurseries, specifically targeting plants during the process of budding or grafting.

The damage caused by this insect is restricted to the areas where the bark has been cut for budding. The adult female midges are attracted to the scent of the sap released from fresh wounds. They lay their eggs in the incision of the rootstock, and the emerging larvae feed on the cambium layer.

The life cycle involves multiple generations per year. The larvae overwinter in the soil or within crevices of the bark in silken cocoons. Once conditions are favourable, they pupate and emerge as adults, ready to infest freshly grafted roses. The synchronization of the pest's flight with the budding season is critical for its success.

The economic impact is significant due to the loss of grafted buds. Infested buds turn brown, shrivel, and fail to sprout. Upon inspection of the affected budding site, one can typically find several tiny, bright orange-red larvae feeding underneath the bark flap, effectively destroying the graft union.

Effective management and control measures include:

• Strict application of grafting tape to tightly seal the budding wound, preventing adult access.
• Use of insecticidal pastes or waxes to treat the cut edges immediately after budding.
• Proper sanitation in the nursery, including the removal and destruction of debris from the previous season.
• Monitoring adult activity to schedule chemical treatments before the peak budding period.