FlytrapCare Carnivorous Plant Forums

I've determined that I have a very big fungus gnat problem. Seems all of my seedlings *usually* just don't do much. My main germination container is doing *so-so*...I believe some capensis that started out as gangbusters are succumbing to the FG larvae. They just languish around, not growing much, and slowly dying out. I had never ID'd a fungus gnat until now. I seriously thought they were t-tiny things like a regular black gnat, but rats!...they're as big as a tree-knot mosquito...maybe even fatter!!!

In the past I'd seen some dead bugs floating in the water of one of my large germination containers but figured "Oh, that fly drowned, it would've made a good meal for somebody..." and didn't think much of it. Then yesterday there was a group of these bug-bodies that had collected together that was the size of a silver dollar floating on top of the water!!! That was simply too much of "something" to not figure out what it was so I started digging and found...FUNGUS GNAT!!!

Right now all that I have in that container are a few flava OP, one Alabamensis x Alabamensis, a fair pot of S. Rosea, and the pot of wide-leaf capensis. The rosea seedlings are doing the best...had great germination and have only lost a few of them and they are getting a little size on them now.
The flava OP seemed to start out strong, but they appear to be declining a bit now. The wide-leaf capensis germinated great but the tiny plants seem to be declining rapidly now, too. The Alabamensis x Alabamensis and a very sparse germination with maybe three of the seeds germinating...one seedling never made it to real-leaf stage. Then, after the last two plants grew a couple of real leaves one of them shriveled up and died. That leaves only one weak-looking Alabamensis.

I've kept the humidity up on these but with the cover cracked an inch or more and most of the time a small fan moving air in the area. Water levels have been roughly 35-40% of the pots' depth (1"-<2"). Temperatures have been mostly good with a few spikes into the mid-to-upper 80's and lows down into the lower 60's...but only on isolated occasions. Lights has been running 16 hours...DLI reads around 23-24 on my phone app.

I haven't seen any worms, but I haven't dug for them. I think the sight of these gnats, though, are most likely telling me I've got an infestation that is greatly affecting these seedlings and that I need to take care of them. I water out of gallon milk jugs...easy to transport, etc.,. I may pour over into a smaller container for watering plants on the shelves. I've got some mosquito dunks and will be putting pieces of these in my jugs in the hopes of wiping the larvae out. The mature sundews apparently have been enjoying them but I'm pretty well convinced the larvae are damaging the seedlings. I've got one loan pot of five or six Filiformis Florida Red White Flowers seedlings that has somehow dodged the "stunt" and seem to be growing ok...they are far away from the germination container the gnats were found it and actually spent time outdoors last summer/fall. How big do seedlings need to get before they can "handle" having fungus gnat larvae in their growing medium?

Fungus Gnats are a major PITA for houseplant growers.
Many of them use Fungus Gnat Traps.
A bowl of water and cider vinegar (or just cider vinegar [or plain vinegar mixed with sugar]) attracts fungus gnats. a few drops of Dawn Dishwashing Soap destroys the surface tension of the liquid and the evil little critters drop below the surface and drown.
Some users add a perforated sheet of Saran Wrap over the bowl to admit FGs but keep down smell and dust.
I don't have first hand experience but a lot of growers swear by these.

Thanks,
Mike T.

Thanks Mike! I've got some cider vinegar on hand so I'll try that, too! I've caught fruit flies with similar traps...plastic bottles with small holes punched in the sides...that might be the route to go. The perforated Saran Wrap is a good idea. I think between the mosquito dunks and the vinegar trap I ought to be able to get them under control. Due to other things, I haven't started my next germination project and I want things to be better conditions before I start that one! Maybe, I can even do that one outside which would be great! The old trailer is a bit dilapidated so the bugs don't surprise me being there...just want to keep them away from the plant room! The adult plants sure have been eating good, though! Even a few of the little kids have snagged a meal!!!

Today is pretty full until (hopefully) late this afternoon. I'll rig some traps and get some mosquito bites soaking in a few water jugs. If that doesn't work I'll bring out my daddy's old Remington Sportsman 58.<grin>

While not as amusing as the bricks, you can add some Mosquto Bits or crushed up Mosquito Dunks to the water that you use to water the plants. Let it sit for a day or two and then use it to top water the plants. The bacteria will kill the larvae but leave the adult gnats for your plants. I'm not sure how long you would need to do this to erradicate the population.

@evenwind, I'm good at taking rabbit trails and your mention of the bricks is sending me down one. Probably 10-12 years ago I got one of those "pre-approved" credit cards in the mail trying to get me to use it. It was from a company a close friend had experienced a nightmare with...exorbitant interest rates and late fees and etc.,. Anyhow they had a postage paid envelope inside their solicitation envelope. I found an old brick and taped the postage paid envelope to it with mailing tape and took it to the post office. We're in a small town and I knew the postmaster so I asked him if the "brick" would mail. He said he didn't see why it wouldn't, the postage paid envelope guaranteed the postage would be paid...so I mailed it. As for as I know that brick went to the credit card company, though I would've loved to have know what it cost them (1st class postage). Who knows, it might've landed in the dumpster after I left the post office but I've always taken a little satisfaction in that little project.

Panman wrote: ↑Sat Feb 25, 2023 6:37 pm While not as amusing as the bricks, you can add some Mosquto Bits or crushed up Mosquito Dunks to the water that you use to water the plants. Let it sit for a day or two and then use it to top water the plants. The bacteria will kill the larvae but leave the adult gnats for your plants. I'm not sure how long you would need to do this to erradicate the population.

I crushed up a dunk and added a teaspoon per gallon to a couple of milk jugs of rainwater. I'll let this steep a couple of days, empty the trays, top water, give it a chance to perk through, and then top the trays off with rainwater and add some of the crushed dunk to the fresh water. Tomorrow I'll work on making a couple of vinegar traps.

evenwind wrote: ↑Sun Feb 26, 2023 12:21 am Nicely done! And I wonder if the credit card company had a bug problem and was frustrated because they only had one brick?

Ya know, I didn't even think of that!!! I might've got a "twofer" and didn't even know it!!!