Why do cabbage worms appear on rooftop vegetables?
Why do cabbage worms appear on rooftop vegetables?
Many people find caterpillars on rooftop vegetables and wonder, how did they get up so high? There are actually several ways:
Butterflies and moths can fly up
- Cabbage white butterflies can fly to the height of multi-story buildings; rooftops are not a problem for them.
- They lay pale yellow eggs on the undersides of leaves.
- Moths (like cutworms) are active at night and also fly to rooftops to lay eggs.
- Eggs hatch in 3-7 days (faster at higher temperatures).
Wind can blow eggs up
- Wind is stronger on rooftops; eggs may be blown in from elsewhere.
- Especially if there are farms or green spaces nearby.
- Newly hatched larvae carried by wind may also land on your vegetables.
Seedlings may carry pests
- Seedlings purchased from the market may already have eggs or small insects.
- They may be too small or still in egg form when bought, not visible to the naked eye.
- Only noticed a few days later when they hatch.
How to prevent?
- Install insect netting, set up fine-mesh netting (mesh ≤1 mm) over vegetable pots. This is the most effective rooftop prevention method.
- Inspect purchased seedlings, check leaf undersides for eggs or small insects.
- Regular preventive spraying, spray dinotefuran-containing insecticide weekly as prevention.
- Quarantine new plants, keep new seedlings isolated for a few days before placing them with others.