The two-spotted spider mite (Tetranychus urticae) is a plant-feeding mite, not an insect, that pierces leaf cells and empties them. Each emptied cell shows as a pale dot, called stippling. Adults are about 0.5 mm long, pale yellow-green with two dark blotches on the body. Heavy populations spin silk that can cover bud sites.
In practice
Growers find them with a 10-20x hand lens on leaf undersides: mites, round clear eggs and cast skins. Speed is the problem. At about 24 °C (75 °F) a generation can finish in under a week, so a few stippled leaves become a webbed canopy within a month. Control rests on early scouting, cooler and more humid air where the stage allows, and predatory mites such as Phytoseiulus persimilis released while numbers are low. Contact sprays belong in veg, not on flowers. Check what is registered for cannabis locally before using any product.
Don't confuse with
- Broad mite and hemp russet mite: far smaller, invisible without 40x or more, and they cause twisting or russeting rather than stippling.
- Thrips damage: silvery streaks with black specks of frass, not fine dots.
- Nutrient spotting: no mites, eggs or webbing under the leaf.
A bud site is a node where flowers form, where leaf meets stem, or a branch tip; training aims to put more of them in strong light.Mites, mostly of the family Phytoseiidae, released as biological control to eat pest mites, thrips larvae, whitefly eggs or fungus gnat larvae.A specialist predatory mite that eats almost only Tetranychus spider mites, eggs to adults; fast-acting on hot spots but starves once prey runs out.Polyphagotarsonemus latus, a microscopic tarsonemid mite whose toxic feeding twists, glazes and stunts new growth; often mistaken for calcium deficiency or heat stress.Aculops cannabicola, a microscopic eriophyid mite specific to cannabis that causes upward leaf curl, bronzing and dull, greasy-looking trichomes.Slender insects about 1-2 mm long, chiefly western flower thrips (Frankliniella occidentalis), that rasp leaf surfaces, leaving silvery streaks dotted with black frass.A generalist-leaning predatory mite that eats spider mites and broad mites, survives on low prey or pollen, and tolerates warmer, drier rooms than Phytoseiulus.Systematic, regular inspection of plants, traps and roots to detect pests and disease early, identify them correctly and record numbers for decisions.The inherited ability of a pest population to survive doses of a pesticide that once controlled it, selected by repeated use of one mode of action.
