The boxwood moth (Cydalima perspectalis) is a nocturnal butterfly native to East Asia. The pests have also been widespread in Germany and neighboring countries since around 2007. As so-called neozoans (i.e. invasive species), they hardly fear any natural enemies in this country, and the animals come from a similar climate and feel very comfortable here.
When is the right time to fight the boxwood borer?
You can find the ideal time to combat the box tree borer by removing white webs from the end of February / beginning of March, removing caterpillars from the beginning of March, installing pheromone traps from the end of April and using biological insecticides from May.
Biology and lifestyle determine the right time
Only those who have detailed information about the life cycle of the box tree borer can tackle the pest effectively. Especially if biological insecticides such as Bacillus thuringiensis are to be used, you should know your enemy. The ideal time to use the spray is when the butterfly is still at the beginning of its development. Since its eggs overwinter inside the boxwood, the caterpillars hatch very early in the year: the big feeding begins around the beginning of March, when temperatures are consistently above around seven to nine degrees Celsius. Special boxwood moth traps also help you discover flying butterflies.
Fighting boxwood borers – when you should do what
As soon as one of them gets caught in one of your traps, you have to act. Adult female butterflies lay up to 150 eggs in their short lifespan, which only lasts around nine days. To prevent the offspring from hatching, you have to be quick. Between three and five populations emerge every year, i.e. i.e. the borer reproduces incredibly quickly. And this is how you fight the animals:
1. End of February / beginning of March:
- examine the inside of the box trees for white webs and cut them out
- If necessary, dust boxwood with algae lime
2. From the beginning of March
- remove hatched caterpillars
- Pruning boxwood
- Covering boxwood trees with plant protection nets
3. End of April / beginning of May
Install pheromone traps for boxwood moths
4. From the beginning / middle of May
- Spray biological insecticides (Bacillus thuringiensis / Azadirachtin)
- mechanical control for weak infestations (high-pressure cleaners, vacuum cleaners, etc.)
Tip
If you want to protect your boxwood from infestation with a plant protection net, choose green nets that are as close-meshed as possible - these are visually less noticeable. The nets can only be removed in autumn, when temperatures remain below seven degrees Celsius.