Thrips

Thrips (order Thysanoptera) are sliver-shaped insects 1-2mm long that attack cannabis by scraping leaf surfaces with their mouthparts and sucking up the released cell contents. The damage signature is distinctive: silvery-bronze patches on upper leaf surfaces (looking metallic in certain light angles), black tar-like fecal deposits on leaves and bud surfaces, distorted new growth that emerges twisted or stunted, and white speckling similar to spider mite damage but without the webbing. Common cannabis thrip species: western flower thrips (Frankliniella occidentalis), onion thrips (Thrips tabaci), and bean thrips (Caliothrips fasciatus). Thrip lifecycle: adult females insert eggs into leaf tissue (causing visible scarring), larvae hatch and feed for 1-2 weeks, mature larvae drop to soil to pupate, adults emerge and the cycle repeats every 20-30 days. Thrips are particularly dangerous because: they can transmit plant viruses including Tobacco Streak Virus and Tomato Spotted Wilt Virus that cause permanent crop damage, populations can establish before damage is noticeable due to their small size, fecal deposits on bud surfaces during flowering ruin product quality, and thrips can complete part of their lifecycle in growing media (soil-dwelling pupal stage) making elimination harder. Treatment: blue sticky traps catch adult thrips and provide population monitoring; predatory mites (Amblyseius cucumeris, Stratiolaelaps scimitus) attack larvae and pupae in growing medium; beneficial nematodes (Steinernema feltiae) target soil-dwelling pupae; insecticidal soap and spinosad sprays kill adults on contact during vegetative stage; pyrethrin for severe infestations. Prevention: yellow sticky traps for monitoring, tight grow room sealing to prevent introduction from outdoor air, inspection and quarantine of new clones, removal of plant debris from soil surface where pupae develop, and aggressive cleanup between grow cycles.