White waxy residue and tiny insects on roots
Colonies build slowly on roots; the plant stalls, wilts and yellows without an obvious cause..
- Also called
- root aphids
- white powder on roots
- bugs on roots
- tiny bugs at the pot bottom
- white waxy roots
Likely causes, most likely first
Ranked for this sign on its own. Your stage, medium and readings change the order, so run the checker for your plant.
PossibleRoot aphids
Fix: Confirm on the roots. Apply soil-dwelling biologicals (Beauveria bassiana drenches, Stratiolaelaps scimitus, Steinernema or Heterorhabditis nematodes), sanitise, and leave a plant-free gap between cycles; dispose of infested media.
Recovery: No live aphids on root checks after 2-3 weeks; growth resumes.
How to confirm it
- Root-ball and drainage-hole insect check. Tip the plant out and inspect the outer roots, pot bottom and drainage holes with a 10x loupe. Root aphids are small, pear-shaped and wingless, often with white waxy flecks; check several plants, and the drain trays, since colonies hide at the pot edge.
- Sticky cards for 1-2 weeks. Hang yellow cards at canopy height and lay one flat on the medium surface; add blue cards for thrips. Count catches every 3-4 days. Rising counts of small dark flies at the medium mean fungus gnats; slender insects mean thrips; white wedge-shaped fliers mean whiteflies; winged aphids mean a colony nearby.
Less likelyMealybugs
Fix: Remove colonies with a cotton bud dipped in 70% isopropyl alcohol (veg only, test a leaf first); release mealybug predators (e.g. Cryptolaemus beetles) or parasitoids; quarantine new stock; discard heavily infested plants.
Recovery: No new cottony clusters after 2 weeks.
How to confirm it
- Magnifier check of leaf undersides and new growth. Use a 10-20x loupe for spider mites, thrips, aphids and whiteflies, and a 30-60x lens or clip-on phone macro for broad and russet mites. Check the undersides of 10 affected leaves across several plants and the newest shoot tips, in white light. Look for moving dots, eggs, shed skins, webbing, slender insects with black specks, and glassy specks on new growth.
Look for
Small pear-shaped insects, often olive to dark with a reddish patch, and white waxy flecks on roots at the pot edge or drain holes..
The full guide: Root aphids (rice root aphid) on indoor cannabis: ID, life cycle in numbers and IPM
Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.
