Nuisance and Biting Flies
Fungus Gnat Control
Fungus Gnat Identification
Fungus gnats are generally small, often tiny, flies with long
legs and long thin wings.
These gnats have vein patterns in the wings.
Eggs of Gnats are hardly visible, oval, smooth, shiny white and semi-transparent.
Larvae or maggots are legless, thread-like, white, shiny blackheaded,
up to 1/4 inch long.
Pupae occur in silk-like cocoons in the soil.
Fungus Gnats Biology and Habits
Gnats reproduce in decaying organic matter that is moist and shaded.
The larvae feed on fungus growing in
the soil and moist organic matter. The larvae will also feed on live plant tissue, especially in root hairs and small roots.
Damage from these Gnats occurs most often in greenhouses or plant beds.
The life cycle is about four weeks, with continuous reproduction in homes or greenhouses where warm temperatures are maintained.
Adults live about 7 to 10 days and deposit eggs on the moist soil surface or in soil cracks. Females lay up to 100 to 300 eggs in batches of 2 to 30 each in decaying organic matter. Eggs hatch in 4 to 6 days; larvae feed for 12 to 14 days.
The pupal stage is about 5 to 6 days.
There are many overlapping generations throughout the year.
Adult Gnats are very attracted to light and so can be
found flying in windows and around lamps.
Inspection for Fungus Gnats
Inspect soil of potted plants.
- When plants are overwatered, increasing moisture it causes conditions for Fungus Gnats to breed.
Look for adult Gnats flying around the plants. This would be an indication of soil under the plants as a breeding source. It may be difficult to find or see larvae of Gnats in soil.
- If no planters or atrium areas are
found to be breeding sources inside, the gnats may be entering
the building from the outside.
Check the plants, soil and organic matter outside near entry points like doors and windows.
- Look for adult Fungus Gnats flying around the plants outside as well.
If landscaped areas are not allowed to dry enough between watering periods, fungi can grow.
- Even without over watering, landscaped areas may retain moisture long enough to permit the fungus to grow, causing conditions for breeding fungus gnats.
- Raking the soil or mulch will killing the existing fungi, as it is exposed to air and light.
- Because fungus gnats are attracted to lights,
occasionally the exterior lighting on the building may be
attracting fungus gnats from neighboring areas.
Also look for water leaks or moisture problems inside such as water stains, swelled wall coverings, peeling paint, ect. If fungus is growing there, these gnats could be breeding there.
- There may be fungi growing in attics or crawlspaces with improper ventilation.
Although it is rare, fungus gnats will breed in such conditions.
- In new construction, moisture normally
gets onto the lumber used to build houses. Occasionally,
surface fungi will begin to grow on wood inside wall voids, which
don't dry out quickly. It is rare, but serious fungus gnat
infestations have developed in new houses inside walls where
fungi has grown. To determine if this is occurring, remove the
plates on wall outlets and attach tape over much of the opening.
Leave a gap between the tape pieces to allow air movement for
the gnats to follow out of the void. If gnats are breeding in
the walls, some of them will invariably become stuck to the
tape. Try this on all wall openings in infested rooms if the
walls are suspected as possible breeding sources.
- Don't stop looking when one breeding
source has been found. In most cases, several breeding sources
will be present.
Fungus Gnat Control
- Locate the breeding source by a complete inspection and remove the soil or dry the soil.
- You may use Pyrethin Aerosol space sprays such as,
V One Pyrethrum Aerosol for immediate knock down.
Using a fly trap like, Matrix II Four Seasons-white or Matrix II Four Seasons - black, would help control many types of flies, including
the Fungus Gnats
- For areas outside that may still retain moisture, after eliminating the breeding sources in the soil, spray a residual treatment such as Bifen IT residual insecticide .
Keep children and pets off sprayed surfaces until it dries. Repeat as needed.
Q: I have gnats and can't get rid of them. I have a dehumidifier and sticky strips, but they are not working.
A: You will need to find the source and remove it. Could be drains, potted plants or even the drip pan under the fridge. Tape the drains shut with clear tape. If gnats are found on the underside of the
tape, then that is where the problem resides. We have a product called Invade Bio Drain Treatment
with enzymes to breakdown the organic material (otherwise known as slime), eliminating the breeding source.
Bio Treatments For Sanitation
Residual Insecticides For Fly Control
Fly Light Traps