# 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.

- Canonical: https://genetixbay.com/knowledge/glossary/broad-mite.html
- Also written: broad mites, Polyphagotarsonemus latus, tropical mite
- Glossary category: Pests and diseases · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

The broad mite (*Polyphagotarsonemus latus*) is a tarsonemid mite about 0.2 mm long, too small to see with the naked eye or a 10x loupe. It feeds on the youngest leaves and [shoot tips](https://genetixbay.com/knowledge/glossary/apical-meristem.md). Its saliva is toxic to the plant, so even a modest population distorts growth far out of proportion to its size.

## In practice

The classic picture is new growth that is twisted, narrow, shiny or glassy, with leaf edges curling down and tips that stall. Growers often chase it as a calcium or boron problem first. Confirming it takes a 40-60x scope or a digital microscope on a growing tip: look for clear oval adults and eggs dotted with white bumps. Broad mites travel on clones, clothing and air currents, so quarantine of incoming cuts is the main defence. [Predatory mites](https://genetixbay.com/knowledge/glossary/predatory-mite.md) such as *[Amblyseius swirskii](https://genetixbay.com/knowledge/glossary/amblyseius-swirskii.md)* and *[Neoseiulus californicus](https://genetixbay.com/knowledge/glossary/neoseiulus-californicus.md)* are used against them. In flower, options shrink sharply; check what is registered for cannabis locally.

## Don't confuse with

- **Hemp russet mite**: an [eriophyid mite](https://genetixbay.com/knowledge/glossary/eriophyid-mite.md) that bronzes and curls leaves upward, usually starting lower on the plant.
- **Calcium or boron deficiency**: no [mites](https://genetixbay.com/knowledge/glossary/two-spotted-spider-mite.md) under magnification, and the damage tracks [root-zone conditions](https://genetixbay.com/knowledge/glossary/root-zone.md).
- **Heat or light stress**: improves when the stress is removed.

## Related terms

[Hemp russet mite](https://genetixbay.com/knowledge/glossary/hemp-russet-mite.md), [Two-spotted spider mite](https://genetixbay.com/knowledge/glossary/two-spotted-spider-mite.md), [Cyclamen mite](https://genetixbay.com/knowledge/glossary/cyclamen-mite.md), [Amblyseius swirskii](https://genetixbay.com/knowledge/glossary/amblyseius-swirskii.md), [Quarantine](https://genetixbay.com/knowledge/glossary/quarantine.md)

## Read more

- [Broad mites on cannabis: life table, spread and control (plus russet mite summary)](https://genetixbay.com/knowledge/pests/broad-russet-mites.md)

## Sources

1. UConn IPM. Managing Broad Mites on Greenhouse Crops. https://ipm.cahnr.uconn.edu/ipm-managing-broad-mites-on-greenhouse-crops
2. Virginia Cooperative Extension. Broad mite (ENTO-587). https://pubs.ext.vt.edu/content/pubs_ext_vt_edu/en/ENTO/ento-587/ento-587.html