How to prevent millipedes from entering the house?

How to prevent millipedes from entering the house?

Prevention requires both outdoor source reduction and physical barriers.

Outdoor source reduction

• Keep the foundation dry and clean; maintain a 30-50 cm debris-free zone—this is the first step.
• Do not stack wood, cardboard boxes, bricks, or leaves against the wall.
• Fill wall cracks with cement or sealant to block entry.
• Regularly remove weeds and dead leaves from the yard.
• Clean drainage ditches regularly to prevent accumulation of decaying plants.

Physical barriers

• Install weather stripping on doors, especially the bottom gap.
• Install screens on windows and vents; repair any damage.
• Replace floor drains with insect-proof types.
• Seal air conditioner pipe entries to eliminate gaps.

Chemical barriers

• Spray a band of bifenthrin-containing household insecticide around the foundation; evening is best (millipedes are most active from dusk to night).
• Millipedes crawling over the treated surface die from contact.
• Reapply after rain to maintain effectiveness.
• Also spray indoor corners and floor cracks for double protection.

Special attention after rain

Millipedes emerge in large numbers after rain, especially in spring and summer (May-August). They are most active at 15-25°C; warm, humid spring and summer are their peak activity periods. Keep doors and windows closed during these times and check indoors promptly. Post-rain is also a good time to reapply insecticide; bifenthrin lasts about 2-4 weeks.