How to Get Rid of Rose Stem Borers Fast (2025 Guide)
As roses come into bud, the sight of branches covered in blooms is a welcome sight. But this is the season of the Rose Stem Girdler, a pest that can cause healthy branches to droop and die overnight!
Characteristics of Rose Stem Girdler Damage
Many gardeners may not have seen an adult stem girdler before, but they have certainly encountered the situation where an otherwise healthy rose shoot suddenly wilts and droops (pictured above). This is usually the result of stem wasps laying eggs inside the branch. When the larvae hatch, they feed inside the branch, blocking water and nutrient transport and causing the branch to wilt. Once symptoms are detected, often the only option is to cut back the affected branches.
Even more frustrating:
Stem wasps prefer to lay their eggs on the strongest branches that should produce the most beautiful flowers
A single rose plant may have 7-8 branches damaged at the same time, resulting in severe damage
Effective Control Strategies
1. Challenges of Controlling Adults
Stem wasp adults are difficult to control because:
- Timing of emergence is unpredictable
- Adults from neighboring gardens may fly in even with early application
- Yellow board traps are limited in their effectiveness because stem wasps are not sensitive to yellow color 2. Yellow board baiting is limited because stem wasps are not sensitive to the color yellow.
2. Solutions for larvae
The key is to stop the larvae from developing. We recommend the use of systemic granules:
- Choose a product with “strong systemic properties” (e.g. “Little White Pill” with furosemide)
- Bury in potting soil, so that the effect is transmitted through the root system to the whole plant
- The larvae feed on the poisonous tissues and die quickly
3. The best time to control
- Early spring: application of systemic insecticides to the soil
- Mid- and late-April (high incidence): foliar application of imidacloprid to provide additional protection
This solution not only controls the stem wasps, but also provides protection against them. This control program not only controls stem wasps, but also prevents common pests such as aphids, whiteflies and thrips at the same time, and the efficacy lasts for 40-60 days.
PRO TIP: Inspect rose branches regularly and cut and destroy any signs of wilting immediately to prevent larvae from continuing to develop.
With this set of preventive measures, your roses will be able to safely survive the high incidence of stem wasps and bloom beautifully as expected!
