Diatomaceous earth
It genuinely works on insects — and the bag beside it in the same farm store can wreck your lungs.
What it is
Fossilized diatom powder that kills insects mechanically, by abrading the waxy cuticle so they dry out. Used in stored grain, in coop bedding, and as a barrier dust.
The numbers
- Food-grade DE only. Pool-filter DE is calcined — heat-treated into crystalline silica — and inhaling it is a genuine, serious respiratory hazard.
- The two bags look nearly identical and sit in the same aisle. This is the most dangerous lookalike in this entire index.
- It only works dry. Damp DE does essentially nothing, so in a humid cellar it's largely inert.
- It is non-selective — it kills beneficial insects on contact too, so it does not belong broadcast around a garden.
Why it's here
Because the mechanism is physical rather than chemical, insects can't develop resistance to it, and for stored grain in a dry climate it's a legitimate tool with a long track record.
The catch
Read the bag, every single time, and wear a mask applying any of it — food-grade included. Any fine dust in the lungs is a bad trade, and the fact that something is safe to *eat* says nothing about whether it's safe to *breathe*. And set expectations: in a humid storeroom, cold and dry does more for your grain than DE ever will.