Field Identification
Small dark flies whose thread-like larvae live in moist organic-rich media, feeding on fungi, decaying matter, and tender roots and stems. Indoors and in propagation they signal overwatering; heavy larval feeding can stunt seedlings.
Adults run on soil surfaces and fly in short hops when disturbed. Larvae are translucent white with a black head, found in the top inch of potting mix.
How to Deal With It
Organic Control Methods
Allow the soil surface to dry between waterings, use well-drained mix, and pasteurize or use reputable sterile media for starts. Screen greenhouse vents.
Apply Bacillus thuringiensis israelensis (Bti) drench for larvae; Steinernema feltiae nematodes parasitize larvae in moist soil. Hypoaspis miles predatory mites feed on eggs and young larvae.
Remove algae and debris on benches, avoid unfinished compost in seed mix, and bottom-water seedlings to keep the surface drier.
Yellow sticky cards trap adults for monitoring and slight reduction; top-dress pots with sand or fine grit to block egg-laying.
Insecticidal soap or neem as soil drench can suppress larvae where labels allow; hydrogen peroxide dilutions are sometimes used cautiously—test on a few plants first.
Let Nature Handle It
Natural Enemies
- Predatory Mites
- Rove Beetles
- Nematodes
Threat Map