All my fungus gnats are gone

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A

ALToronto

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I had a terrible infestation all through spring and summer, and suddenly, I have none. I'm not sure if I did something right, or if it's a seasonal thing, but I'd like to know so next time I get an infestation, I'll know how to get rid of them.

I used a sulfur spray to reduce the fungal spread in the media, about once every 2 weeks. I also ended up with lots of tiny spiders all through my collection, and they've been busy weaving webs between the pots. There are quite a few dessicated gnats still stuck in those webs. I also use coiled CFLs to supplement what daylight gets through the windows. There have been lots of fungus gnat corpses stuck to the lamp coils. Obviously, these remedies helped, but I never thought I would get perfect results with any or all of them.

So is it something I did or just a change of seasons?
 
I'm pretty sure all of the above have contributed to your success. Hopefully permanently.

However, if your conditions are anything like mine, now that Fall has arrived, your growing temps are cooling down, which means that the gnats' lifecycle is slowing down. So, it is possible they aren't gone, it's just that it's taking longer for the eggs to hatch and the maggots to mature to adulthood. Meanwhile, the adults have very short lifespans, so they've all died off naturally, been eaten or flown into the artificial suns.
 
if the gnats dont have any hospitable place to breed inside or outside (only important if you have a GH), there will be a lot less. I live in a climate where they can breed outside my GH all year round and just migrate inside my GH but they never seem to be able to reproduce inside ( I have looked closely for maggots and never find them inside). During the summer I rarely see gnats as they can just stay outside but once it cools down into the high forties outside i see a lot more in my GH.
 
One thing I noticed at old work, was if a floor had been sprayed with green shield and puddles remained they would head for the puddles and be killed. The chemical breaks the surface tension of the water (I'm assuming) and when they try to land on the surface they sink and drown. A pie pan with some green shield could make a nice bug trap


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Well usually they can float on top (at least the shore flies can do that quite handily), so if they were in the liquid they would die whether or not it was water or greenshield. I guess the fumes of the chemical could overwhelm them if they were close...


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The spiders will have to learn to hunt the little thrip-sized bugs that have taken up residence in my phal compots. They're not thrips, and they're much fatter than thrips. They also jump like fleas and eat something other than phal roots and leaves (probably algae growing on the sphagnum).

I'm enjoying the development of my insect ecosystem almost as much as the orchids. I think a praying mantis is next on my acquisitions list.
 
The spiders will have to learn to hunt the little thrip-sized bugs that have taken up residence in my phal compots. They're not thrips, and they're much fatter than thrips. They also jump like fleas and eat something other than phal roots and leaves (probably algae growing on the sphagnum).

I'm enjoying the development of my insect ecosystem almost as much as the orchids. I think a praying mantis is next on my acquisitions list.

Sounds like Springtails.
 
I hate springtails! :mad:

Why? As long as they're not eating my orchids or biting me or any other red-blooded beings that live in my house, I don't mind them. I might have a problem with Florida cockroaches, but thankfully we don't get them here. And aren't springtails also predators to nasty insects?
 
I have had a problem with fungal gnats in the past.
Try pushing back your regular watering schedule by
a day or two. Hang a fly catching strip near your
orchid plants. Water all your plants with hydrogen
peroxide once. Two or three days later spray the
top of your potting mix with hydrogen peroxide.
It may also help to lift pot up to your ear after
watering...sounds like Rice Krispies...now visualize
those dreaded gnats exploding. It works like a charm.
J.
 
Bad news! They are eating your orchids!

There is zero damage to leaves and roots of my phal seedlings. And this is an excerpt from Wikipedia:

"...by their capacity to carry spores of mycorrhizal fungi and mycorrhiza-helper bacteria on their tegument, soil springtails play a positive role in the establishment of plant-fungal symbioses and thus are beneficial to agriculture.[32] They also contribute to controlling plant fungal diseases through their active consumption of mycelia and spores of damping-off and pathogenic fungi.[33][34] It has been suggested that they could be reared to be used for the control of pathogenic fungi in greenhouses and other indoor cultures."

Some springtail species do eat plants, but mine don't seem to. I think they just eat the algae, and I have no shortage of that in my compots.
 
Gnats

I've used predatory nematodes to dispatch the fungus gnats in the past. They work for the tropical plants in the house too.
 

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