Crushed eggshells deter slugs.
Contested
Eggshells don't reliably deter slugs — they cross far sharper surfaces on their mucus layer, and the "barrier" weathers away fast. Use beer traps, night hand-picking, or iron-phosphate bait; put the shells in the compost for the calcium.
What is actually known
The claim is that sharp edges form a barrier slugs won't cross. Slugs glide on a mucus layer and cross genuinely sharp surfaces; crushed eggshell weathers to blunt fragments quickly and does not reliably stop them. The shells do add a little calcium as they break down — that is their real contribution, in the compost, not as a barrier.
Evidence: not yet confirmed against its 1 source.
what this rests on - one pointer
slug locomotion on mucus; barrier trials do not support
When would that grow at your place? →
Cite this page
Milpa Gardens. "Crushed eggshells deter slugs." Evidence grade: Contested. https://milpa.garden/beliefs/eggshells-slugs/
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