# Shore fly

> Stocky dark flies of the genus Scatella (family Ephydridae) that breed in algae on wet surfaces; mostly a nuisance and contamination issue rather than a root feeder.

- Canonical: https://genetixbay.com/knowledge/glossary/shore-fly.html
- Also written: shore flies, Scatella, Scatella stagnalis, Ephydridae
- Glossary category: Pests and diseases · Evidence: Supported
- 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"

Shore flies are small flies of the family Ephydridae, mainly *Scatella* species, about 2-3 mm long. They look like stout house flies with short antennae and dark wings marked by five or so pale spots. Larvae feed on algae and microbial films on wet media, floors, benches and drip trays.

## In practice

Shore flies turn up wherever algae grows: wet [rockwool cubes](https://genetixbay.com/knowledge/glossary/rockwool.md), flooded trays, hydro reservoirs open to light and puddled floors. They are not considered major root feeders, unlike [fungus gnat](https://genetixbay.com/knowledge/glossary/fungus-gnat.md) larvae, but adults leave dark specks of [frass](https://genetixbay.com/knowledge/glossary/frass.md) on leaves and can carry pathogen spores between plants. Control is mostly sanitation and water management: cover cubes and reservoirs, remove standing water, and reduce algae on surfaces. [Yellow sticky traps](https://genetixbay.com/knowledge/glossary/sticky-trap.md) show numbers. Some fungus gnat predators also take shore fly larvae, but fixing the algae solves most cases.

## Don't confuse with

- **Fungus gnat**: slender, long-legged and weak fliers; larvae eat roots.
- **Fruit fly**: red eyes, attracted to fermenting material.
- **Whitefly**: white wings, lives on leaves.

## Related terms

[Fungus gnat](https://genetixbay.com/knowledge/glossary/fungus-gnat.md), [Sticky trap](https://genetixbay.com/knowledge/glossary/sticky-trap.md), [Sanitation](https://genetixbay.com/knowledge/glossary/sanitation.md), [Biofilm](https://genetixbay.com/knowledge/glossary/biofilm.md)

## Read more

- [Fungus gnats: the watering problem with wings](https://genetixbay.com/knowledge/pests/fungus-gnats.md)

## Sources

1. UC IPM. Pest Notes: Fungus Gnats (Publication 7448). https://ipm.ucanr.edu/legacy_assets/pdf/pestnotes/pnfungusgnats.pdf
2. Michigan State University Extension. Managing greenhouse insects. https://www.canr.msu.edu/news/managing_greenhouse_insects