We’ve had a problem with fungus gnats inside and outside for the past month or so. At least seven of our neighbors have the same problem; I also noticed them in the windows at my dentist’s office and yesterday at a restaurant yesterday about 8 miles from here.
I’ve been told they’re coming from my houseplants, but I’ve checked the soil (I do not over water) and they’re not in the plants, however, I did purchase a granular product which I will place in the plant soil later today.
I occasionally see one flying through the air, but they’re mostly on windows. I’ve killed in excess of 50 in a few minutes at the large window in our living room; go back a little while later, and they’re there again. An exterminator told me they’d disappear after frost. We’ve had frost; it slows them down for a day (as does rainy weather), but then they come right back. I’m really afraid that we’ll have to learn to live with them.
We do live in mushroom country (Kennett Square, PA), but we’ve been here for 12 years and have never had them until this year. Is it possible we’ve had just right weather conditions? What do you think? Any thoughts you have would be really appreciated.
PS: You’ve helped us with springtails about a year or so ago. Those are now under control. Thank you!
In fact FUNGUS GNATS routinely become a problem inside homes during the colder months of the year. No doubt houseplants are the most common location where they’ll congregate and breed. This FUNGUS GNAT IN PLANTS problem discusses the best option for treating soil. I prefer this treatment over granules because it works immediately. And though you don’t think the plants are the problem, it’s imperative you start there and then branch out to other areas of the home if treating the plant soil doesn’t solve the problem. Remember, you won’t see any gnats in the plants because they’re only active there when developing as young larvae. Once they hatch out as adults, they’ll leave the plants and rarely if ever return. 99.9% of their life will be spent flying around the house and only females will forage to places where they can lay eggs like the soil and once done, they’ll leave right away. So with this in mind, it’s important to treat the soil because it’s usually a hot spot but more important will be the spots where they’re seen. And from what you’re describing, this sounds likes it the windows.
So what can you do for the windows? Fortunately there are two treatment options you should consider that would no doubt help. The first would be to lightly apply a pre-mixed formulation of BIFEN IT to the window frame around the glass. This active is odorless, lasts a long time when used inside the home and is very active on flies and gnats. You’d only need to mix a small amount, like .1/4 to 1/2 oz per gallon of water, so there would very little product being actually used to treat all the areas where they are active. I’d recommend mixing up a tank full, maybe just 1/2 gallon to start, and then using a paint brush to lightly apply the mixture to the target sites. Bifen can actually be used on plants so you could treat the houseplants with any left over spray by drenching the soil. Also, Bifen is great outside on the landscape vegetation for most any pest including ants and mosquitoes.
The second option would be to install some AEROSOL MACHINES we have listed in this general GNAT POST. This approach would be easier to employ but more general and if you don’t have enough machines distributed around the home, the flies will no doubt still be a problem.
In the end, trying to locate the source of the moisture would be ideal. Once dried or treated, you should be able to stop the cycle. I mostly see where houseplants are to blame but other areas that can easily cause a problem include garbage disposal systems found in most kitchen sinks, garbage bin areas, kitty litter, refrigerators, ice making machines, hot water heaters, air blowing systems and humidifiers or dehumidifiers. Remember, the fungus gnat will only remain in these areas as a larvae. Once an adult, it will only go back to such an area to lay eggs but will spend 99.9% of it’s life away from nesting sites so don’t think you need to see them on the plants for this to be their nest site because that won’t happen.
Here are direct links to the information and products listed above:
Fungus Gnat Control: http://www.bugspray.com/catalog/products/page306.html#fungus_flies
How to treat Fungus Gnats in plants: https://www.bugspray.net/fungus-gnats/fungus-gnat-problem-in-plants-or-house.html
Bifen It: http://www.bugspray.com/item/bifen_it.html
Aerosol Machines: http://www.bugspray.com/catalog/products/page1813.html
How to treat Gnats in house: https://www.bugspray.net/gnats/gnat-problem-in-house.html
William Pezzotti says
I too am having an issue with fungus gnats in my home and around my windows. I also live in Kennett Square,PA. This seems to be a huge issue for us in the fall and mostly affects our second floor, specifically my master bedroom and master bathroom. I do not have any house plants, and can not figure out how they are getting in. When you look out the window they are at times swarming around. I have been using bug spray but they keep coming back. What are they attracted too, and how can I get rid of them. I live in a townhome community and many neighbors are having the same issue.
Tech Support says
@William Pezzotti: There are several things that will attract gnats. First is moisture and second is food. Any type of organic matter will attract them and this would be a food source. And when you have moisture and warm enough temps like those found around most any window during the fall and winter months, either mold or fungus will grow. This can become the food for a wide range of pests including gnats.
Does this mean you have some kind of major leak or construction flaw on your house? No. In most cases the small minute cracks barely detectable by the eye is all it takes for gnats to live and thrive. And yes, you should look over the windows and areas close by to make sure they’re not in need of some caulking. But in most cases a treatment or two with the Bifen IT mentioned above will knock them right out whether you seal cracks first or not.
So to get rid of them, you’ll need to see if some sealing is needed by window frames, door frames, etc. If so, take care of that first. Right after the sealant dries, you can spray with some Bifen and your problem will be resolved. Alternatively you can use just the Bifen if you don’t think there are many access points and it will no doubt keep them under control.
Lastly, treat around the exterior of the home every 2-3 months to prevent future infestations. Remember, the home is a great place for many pests to nest so don’t give them the chance because once they do, some will start getting inside.
We have fungus gnat swarms mostly dead in areas of my mothers beach condo mostly near doors. It looks like chocolate sprinkles on the floor. We went three weeks ago to the beach condo and there were a lot of them mostly dead, some flying around still, but this week there were thousands it made me sick, we have no plants. Just a summer condo built on sand. Also no other tenant has them? We had a problem last year with raccoons living in our attic. We could smell the urine. Is it possible these fungus gnat swarms are from the raccoons urine and feces?
Tech Support says
Fungus gnats will thrive during the warm seasons of the year. Typically this is from spring though fall. And they love rocks and slabs. So if the home has an outside patio deck or if its built on a slab, they are most likely living under ground and from there, coming up when cycles mature.
The good news is they’re easy to control. When problems like this arise inside condo’s, the best way to treat is to set up an Aerosol Machine with some Metered Insecticide. These machines will run continuously going off every 15 minutes. When they go off, they release a small blast of pyrethrin based insecticide that will kill anything flying like gnats or mosquitoes. Set one of these up in any room up to 20 ft by 20 ft and turn it on. At that point the machine will do the job with refills only needing to be replaced every 30-40 days. Keep one of these running when you’re visiting the condo or when away. By killing all that come out in the living space, they won’t be able to mate and lay eggs so eventually, the problem will go away whereas right now, they keep replenishing themselves by laying eggs since you aren’t treating.
Here are links to these items in our cart:
Aerosol 1000: http://www.bugspraycart.com/equipment/foggers/aerosol-dispenser-1000
Metered Air: http://www.bugspraycart.com/insecticide/aerosol/purge-iii-6-25-oz
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