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Stop Fungus Gnats

Monitoring

How do you know it's actually working?

Written by Mustafa Ayan Fact-checked against university extension/IPM sources Last reviewed: September 19, 2026

Direct answer

Watch the trend on a sticky trap over several days, not whether the count has hit zero. Eggs and larvae already in the soil when you started keep developing on their own schedule, so a falling — not flat, not zero-yet — trap count is the real early signal that moisture control and any larval treatment are doing their job.

Signs it's working

  • Your sticky trap count is trending down week over week, even if it isn't zero
  • Fewer adults appear at windows or on other plants nearby, not just the treated pot
  • A potato test shows fewer or no larvae compared to when you started
  • The soil surface is visibly, consistently drier between waterings

Signs it's stalled

  • Trap counts stay flat or climb for more than a week of consistent treatment
  • New adults keep appearing from a pot you haven't actually treated
  • The soil surface still feels damp within a day of watering, despite intending to let it dry
  • You've only treated one pot while others nearby stay untouched

Why "zero adults" is the wrong first milestone

Adults that were already pupae when you started treating will still emerge — that's expected, not a sign the plan has failed. Because egg-to-adult takes roughly 3–4 weeks indoors, and every stage overlaps, a working plan usually looks like a gradually shrinking trap count over one to a few weeks, not a clean stop. Judging progress by a single day's count, instead of the trend across several, is one of the most common reasons people give up on a plan that was actually working.

If the trend really is flat or rising

That's a genuinely different situation from "still going, but slowly" — it usually means the soil is still staying wetter than intended, a second untreated pot nearby is reseeding the room, or the identification was wrong to begin with. The troubleshooting self-check walks through each of those directly.

Track progress with the 7-day plan

Sources