by Tony
Fungus Gnat Larvae in my peas
10:46 pm in Seeking Advice by Tony
I’ll be posting some information on my second WF hopefully by this weekend, but I wanted to throw this out to see what you think. I have peas on the bottom level and lettuce on the next level up. The peas are about 60 days old now and doing well, and these small bugs just showed up! They look like some type of borer. They have a white/clear body and a black head. Any ideas what they are and how they might get here? On the seeds? In my rock wool supply? In my rain water?
Am I the only one with bug problems? At least my spider mites are gone now…
Bugs In My Peas
A big THANKS to @samenrahmen for knowing what these little buggers were. Knowing what you are dealing with is half the battle and it all makes sense now.
To document this a bit more, I am adding a few more pictures to this post and changing the title. Here is an example of the adult that has been buzing around that I just smashed. I am surprised that my camera took a decent picture of it as it is only about 1 mm long.
Fungus Gnat Adult
This now explains the dying leaves on the plant. The lower leaves are drying out and dying and this symptom is slowly working its way up the vine. I assume this can be caused by them feeding on my roots. Hopefully, I have caught this in time as the upper part of the plant is flowering nicely and peas are starting to grow.
Gnat Fly Leaf Damage
In reading up on these gnats, I see that they like really wet conditions so I am going to cut way back on the watering cycles. I had been thinking it was a bit too wet. I had gotten a new air pump when I started this second WF and have not gotten a good feel for how much water the peas and lettuce like.
Adult Gnat Flies on Fly Paper
I bought some fly paper type stuff from HomeDepot. It is the darker part of the image above. It is a long piece of sticky plastic and came all rolled up in a tube. It is incredibly sticky and does not want to straighten out. To make it easier to work with I cut it into smaller strips and put it on some yellow construction paper. It naturally wanted to curl up so I made in into a cylindar and put the tie on it. I quickly learned to use rubber gloves. In a matter of 24 hours, there were 12 flies stuck on it.
I am giving them less water and I have also taken out as much of the rockwool as possible to give them a smaller home. The majority of the roots on this one are actually in the resevoir below. It had turned itself into a deep water culture. I have also tried some hydrogen peroxide since that is what I had already in the house.
As a side note, everything I have been doing has been with rockwool. When I first started and went to the hydroponics store, they were out of the small bags of the clay pellets and I did not want to buy the big “life time” supply bag. So this is what the recommended instead. The one advantage has been that I can “accidentally” unplug the pump for a day and the plants don’t die.
These are the larvae of fungus gnats, the small black flies you encounter wherever there is a combination of soil and moisture. If your plants are doing fine, they shouldn’t be a problem, otherwise Neem will (temporarily) help against them.
Perhaps someone else could answer this: Are they doing well in expanded clay, too ?
Try adding some hydrogen peroxide to your nutes. Up to 30ml per gal has been show to be beneficial to plants, and it may just kill those little root suckers (or whatever they are). Neems oil is good for many pests, but as far as I know; it really works for pests that attack the leaves, not so much the roots.
Are you just growing in loose rock-wool, or is there clay underneath? I suspect the little wormies wouldn’t like the clay as much. If you were to pick out as much of the wool as you can with out hurting the plant you might cut the population down to something that wouldn’t do noticeable harm.
For my setup I went to a pet store and bought a little T-shaped valve for regulating the air going into my air lift. They are around 3$, maybe that would help? This way instead of watering them less often you just give them less water.
Owen, thanks for trusting me one this one
It really does work; I done it a few times over the last year.
Unlike peroxide, the Neem can stay in the water for longer, stopping the next generation of larvae as well.
And no, Mel, the only soil without fungus gnats in them is absolutely dry one ! One drop of moisture, and they’re there.
Expanded clay & constantly flowing water probably is the best solution for keeping them out.
You could also use nematodes, like Steinernema feltiae, they are the natural predators of the larvae. No need to add chemicals