# Sticky trap

> A coloured card coated in non-drying glue that catches flying insects, used mainly to monitor pest trends: yellow for gnats, whiteflies and aphids, blue for thrips.

- Canonical: https://genetixbay.com/knowledge/glossary/sticky-trap.html
- Also written: sticky traps, sticky card, sticky cards, yellow sticky trap, blue sticky trap, glue trap
- 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"

A sticky trap is a plastic or card sheet, usually yellow or blue, coated with a non-drying adhesive. Flying insects attracted to the colour land and stick. Yellow attracts [fungus gnats](https://genetixbay.com/knowledge/glossary/fungus-gnat.md), [shore flies](https://genetixbay.com/knowledge/glossary/shore-fly.md), whiteflies, [winged aphids](https://genetixbay.com/knowledge/glossary/alate.md), leafminers and [thrips](https://genetixbay.com/knowledge/glossary/thrips.md); blue is somewhat more attractive to thrips. They are first a monitoring tool and only secondarily a control.

## In practice

Growers hang traps just above the canopy for flying [foliar](https://genetixbay.com/knowledge/glossary/foliar-feeding.md) pests and close to the medium surface for fungus gnats, at a density such as one per few square metres. Each week they count catches by type on a marked area, write it down and replace the card. Rising counts are the early warning. Traps also catch [beneficial insects](https://genetixbay.com/knowledge/glossary/biological-control.md) such as [parasitic wasps](https://genetixbay.com/knowledge/glossary/aphidius.md) and Orius, so they are often removed or reduced while releasing flying beneficials. Keep traps clear of buds and hair.

## Don't confuse with

- **Scouting**: looking at plants directly; traps add a record of flying adults.
- **Mass trapping**: many traps to reduce numbers; rarely enough by itself.
- **Pheromone trap**: uses a sex attractant for specific moths.

## Related terms

[Scouting](https://genetixbay.com/knowledge/glossary/scouting.md), [Action threshold](https://genetixbay.com/knowledge/glossary/action-threshold.md), [Fungus gnat](https://genetixbay.com/knowledge/glossary/fungus-gnat.md), [Thrips](https://genetixbay.com/knowledge/glossary/thrips.md), [Whitefly](https://genetixbay.com/knowledge/glossary/whitefly.md)

## Read more

- [Fungus gnats: the watering problem with wings](https://genetixbay.com/knowledge/pests/fungus-gnats.md)
- [Thrips on cannabis: life table, temperature, scouting and biological control](https://genetixbay.com/knowledge/pests/thrips.md)

## Sources

1. Michigan State University Extension. Managing greenhouse insects. https://www.canr.msu.edu/news/managing_greenhouse_insects
2. UC IPM. Pest Notes: Thrips (Publication 7429). https://ipm.ucanr.edu/PMG/PESTNOTES/pn7429.html