Gnats in the kitchen almost always breed in the kitchen. The small flies around the sink, the fruit bowl, or the garbage disposal are not coming in from outside — they are breeding in the drain slime, the fermenting fruit, or the residue in the disposal. Treating the air does not end kitchen gnats. Finding the source does.
The visit for kitchen gnats is a source hunt. The inspection checks the drain, the disposal, the fruit bowl, the recycling bin, and any leak under the sink, and the plan is built from what is found. Most kitchen gnat problems end when the source is dried out or removed — and the ones that do not end usually have a second source the first look missed.
TL;DR
Problem: small flies around the kitchen sink, fruit bowl, or disposal.
Solution: find the breeding source — drain, fruit, or disposal — dry it out and clean it.
When to call: when gnats return after cleaning, or when you cannot find the source.
Drain gnats: the sink and disposal
Drain flies breed in the slime inside the drain pipe, and the garbage disposal holds the same residue. They are most common in drains that are used rarely, where the slime builds up undisturbed. The fix starts with cleaning: a stiff brush inside the drain, hot water, and a cleaned disposal remove the breeding surface. A drain that is cleaned and then used regularly rarely holds gnats again. If the flies return within days, the breeding surface is deeper in the pipe, and the visit checks the trap and the line below the sink.
Fruit flies: the bowl and the bin
Fruit flies breed on fermenting fruit, vegetables, and the residue in a recycling bin. A bowl of fruit on the counter, a potato gone soft in the pantry, or a bin that has not been rinsed will hold them. The fix is to remove the breeding material — the fruit, the soft potato, the bin residue — and to keep counters wiped and bins rinsed. A vinegar trap catches the adults, but the trap alone does not end the problem while the breeding material is still there.
The leak under the sink
A slow leak under the sink keeps the cabinet damp, and damp wood and standing water breed gnats and draw other pests. The inspection checks under the sink for the leak, because the gnats are following the water. Fixing the leak and drying the cabinet ends the breeding source that cleaning alone cannot reach.
When cleaning does not hold
If gnats return within a week of cleaning, there is a second source — a second drain, a plant in the kitchen window, a leak under the sink, or a garbage can in the garage. The visit hunts for the second source when the first cleaning does not hold, and the plan covers it.
Steps
Watch where they gather
The sink, the fruit bowl, the disposal, the window plant — the gathering point is usually within a few feet of the breeding source.
Clean the drain and disposal
Brush the drain, run hot water, clean the disposal. The slime and residue are what the larvae feed on.
Remove the fruit and rinse the bin
Take away the fermenting fruit, rinse the recycling bin, wipe the counters. The breeding material goes first.
Fix the leak
Check under the sink for a slow leak. Dry the cabinet and fix the leak, or the gnats return.