Field Identification
Small moth-like flies that breed in algae and biofilm on wet greenhouse floors, capillary mats, and saucers. Adults speckle foliage with fly specks and are a nuisance indicator of chronic overwatering, not always direct feeders.
Chunky body, short antennae, wings often spotted or smoky; larvae live in slimy green algae films. Often confused with fungus gnats but run on surfaces more like tiny houseflies and associate with standing wet, not just moist peat.
How to Deal With It
Organic Control Methods
Soap or neem directed at adults is secondary—focus on habitat removal; Bacillus thuringiensis israelensis drenches target larvae in algae films where labeled for that use.
Predatory rove beetles (e.g., Dalotia coriaria) and hypoaspis soil mites reduce larvae sharing the same algae habitat; nematodes help in some propagation systems.
Dry the bench top between waterings; improve drainage; pressure-wash algae from walkways; avoid bottom heat that keeps mats soggy.
Yellow sticky cards catch adults for monitoring; vacuum adults during peak emergence in enclosed houses.
Sterilize reused trays; fix leaks and puddles; keep hose ends off the floor.
Let Nature Handle It
Natural Enemies
- Dalotia coriaria
- Stratiolaelaps scimitus
- Rove Beetles
Threat Map