Eriophyid mites (family Eriophyidae) are the smallest plant-feeding mites, roughly 0.2 mm long, worm- or carrot-shaped, with two pairs of legs at the front end instead of four. They include rust, russet, gall and bud mites. The hemp russet mite, Aculops cannabicola, is the cannabis species; Colorado State notes it cannot be seen without magnification.
In practice
Eriophyids are found by their damage (bronzing, upward curling, brittle leaves) and confirmed with a 40-60x loupe or microscope, often by lifting mites onto clear tape. They spread on clones and air currents. Their size and speed of increase make them a zero-tolerance pest in mother rooms.
Don't confuse with
- Spider mites: much larger, four pairs of legs, visible at 10x.
- Tarsonemid mites: broad and cyclamen mites, also tiny but with four pairs of legs.
Tetranychus urticae, the commonest cannabis mite indoors: a 0.5 mm sap-feeder that stipples leaves pale and spins webbing, breeding fastest in hot, dry rooms.Aculops cannabicola, a microscopic eriophyid mite specific to cannabis that causes upward leaf curl, bronzing and dull, greasy-looking trichomes.The single botanical species, in the family Cannabaceae, that covers all hemp and drug-type cannabis; "L." credits Linnaeus, who named it in 1753.A small handheld magnifier, typically 30-60x for cannabis use, used to inspect trichome heads and spot pests and male flowers.The thread-footed mite family that includes broad mites and cyclamen mites; tiny pests of growing tips, best seen at 40x or more.Phytonemus pallidus, a tarsonemid mite related to the broad mite that distorts new growth on many ornamentals; rarely reported on cannabis and often confused with broad mite.Polyphagotarsonemus latus, a microscopic tarsonemid mite whose toxic feeding twists, glazes and stunts new growth; often mistaken for calcium deficiency or heat stress.Mites, mostly of the family Phytoseiidae, released as biological control to eat pest mites, thrips larvae, whitefly eggs or fungus gnat larvae.
