Massive Millipede Invasion in Basement After Flooding

Millipedes in pool skimmer basket

Millipedes next to penny for scale

Pennsylvania basement apartment invaded by thousands of millipedes since mid-June after extreme rain and 3-inch flood. Dehumidifier running. Spectracide sprays failed. They're in drop ceiling, pool skimmer.

Why They're There

Saturated soils force millipedes (and springtails) to seek drier ground. They migrate en masse to structures. Insecticides don't stop pressure from waterlogged soil.

What Works

• Wait for soils to dry. Migration stops naturally.
• Physical removal: Sweep, vacuum, shop-vac.
• Exclusion: Seal cracks, install door sweeps, fine mesh on vents.
• Perimeter barrier: Diatomaceous earth or granular bait (e.g., Niban) around foundation after soils dry.

They're harmless—no bite, no damage. Just a nuisance. Patience + exclusion = resolution.