Diatomaceous earth keep away crawling insects that have soft or thin outer shells. This includes ants, aphids, earwigs, and many beetles. The pests DE controls share one trait: they cannot survive DE contact when it stays dry.
I have used DE against ants, flea beetles, and aphids with great success in my garden over the years. The powder stopped ant trails within days and cut down aphid numbers on my pepper plants. Earwigs stayed out of my raised beds after I dusted the edges around them.
What insects DE kills depends on their body type and shell thickness. DE works by absorbing the waxy oils on insect shells and causing them to dry out. Soft-bodied pests like aphids die fast. Thin-shelled crawlers like ants take 24-72 hours to show effects from the powder.
Ants and Crawlers
- Ant species: Most common garden ants die after crossing your DE barriers within 24-48 hours of contact.
- Earwigs: These pests avoid DE-treated areas and die if forced to cross through fresh powder you lay down.
- Silverfish: Effective control in dry areas like your sheds, garages, and indoor spaces near your gardens.
Garden Pests
- Aphids: Direct dusting kills aphids on your plants but rain washes it away and requires you to reapply often.
- Flea beetles: DE barriers around your plants reduce damage from these small jumping pests with thin shells.
- Thrips: These tiny pests are soft-bodied and show good response to your DE treatment when kept dry.
Indoor Pests
- Roaches: DE works well in dry indoor areas where roaches travel and hide during the daytime hours.
- Bed bugs: Effective as part of your treatment plan but requires dry conditions and direct contact to work.
- Fleas: Helps you control flea populations in carpets and pet areas when you apply and leave it dry.
Some pests resist DE because of their shell thickness or body moisture. UMN Extension notes that hard-bodied insects like Japanese beetles resist DE treatment. Slugs and snails stay wet enough that DE cannot dry them out at all.
I tried DE against slugs one season and saw zero results from my efforts. Their slimy coating blocks DE from working on them. For slugs you need iron phosphate bait or beer traps instead. Flying insects also avoid DE since they rarely walk through your treated areas.
Match your pest problem to the diatomaceous earth pest list before you apply. Check if your target pest crawls on the ground and has a thin or soft shell. If yes, DE should work well for you. If no, save your powder and try a different control method that fits your pest better.
Read the full article: Diatomaceous Earth Garden: Complete Guide
