Eliminate Fungus Gnats for Good

Identify the Enemy

Fungus gnats (1/16‑1/8″) resemble tiny mosquitoes. Weak fliers, they rest on soil and fly up when disturbed. Females lay 300 eggs in moist soil; larvae (dark head, whitish body) feed on roots, stressing plants. First signs: wilting, decline.

Prevention & Control

• Dry out soil: Let top layer dry between waterings. Overwatering is the #1 cause.
• Inspect before bringing plants in: Fall/winter is high risk.
• Repot if drainage is poor.
• Store extra potting soil dry in sealed containers.
• Fix leaks and standing water in greenhouses.

Monitoring & Treatment

• Yellow sticky traps laid horizontally on pot rims catch adults.
• If numbers are high, repot in sterile mix after washing roots.
• Beneficial nematodes (Scanmask, Nemasys) kill larvae safely. Apply when soil isn’t frozen; effective for months.

Act early—gnats multiply fast.