Tiny moving dots under the leaves
Found on scouting; numbers can double in a few days when hot and dry..
- Also called
- tiny bugs under leaves
- moving specks
- mites under leaves
- little red dots moving
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.
LikelyTwospotted spider mites
Fix: Act now: they breed fastest hot and dry. Remove the worst leaves into a sealed bag, cool the room and raise RH a little (in veg), release predatory mites (Phytoseiulus persimilis for hot spots, Neoseiulus californicus as a preventive) before numbers explode. Soaps or horticultural oils only in veg, never on buds. Quarantine new clones.
Recovery: No new stippling on new leaves and no live mites at 10-20x after 7-14 days.
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.
- Tap a branch over white paper. Hold white paper under a branch or bud and tap it sharply 3-4 times. Watch the paper for 30 seconds: moving specks are mites or thrips (smear them; spider mites leave red-brown or green streaks), larger fliers are whiteflies. A quick whole-room screen before the magnifier.
Look for
10-20x photo of the leaf underside: eight-legged mites, often with two dark spots, and round eggs..
The full guide: Spider mites on cannabis: life tables, ID 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.
