How long does it take for DE to kill fleas?

Diatomaceous earth (DE) can take several days to a few weeks to effectively kill fleas. The powder works by dehydrating the fleas, damaging their exoskeletons when they come into contact with it, but results may vary based on the severity of the infestation and environmental conditions. For best results, it’s important to apply DE thoroughly in areas where fleas are present and to reapply as needed. Regular vacuuming and cleaning can also help accelerate the process.