Some question about carrot flies, but not only!

For the first time I thought of planting vegetables. Long story short, so far the ones that made it are: carrots and potatoes.

I noticed yesterday that there were a few of super-tiny flies that have been hanging inside these 2 grow bags on my balcony. They were there today too. I had the impression that carrot flies tend to be on be on the ground like, not higher up. Is it the case? Is it possible that it's a potato thingy that I am just not well informed about?

Could it also just be nothing to worry about? Temperatures around here easily get to 40°C, so we're no strangers to flies of all sizes. Also my compost bin is quite close, so I thought that maybe they could be coming out of there, but I never saw any like them before (and at the same place there were some secculent and cacti previously, but no tiny flies). Is it possible that they are hanging around just because I water them daily (in contrast to the secculent that need watering seldom)?

So, any info, tip, trick or link is more than welcome! And thank you for reading all this :)

3 points · 6 comments · view on lemmy.world

6 Comments

zeppo@lemmy.world · 5 pts · 13d (5 replies)

Sounds like fungus gnats. They’re a mild hazard to plants and are somewhat annoying.

https://www.thespruce.com/how-i-finally-got-rid-of-fungus-gnats-8678354 Is a pretty decent rundown of what they are and what you can do.

solo@slrpnk.net · 3 pts · 13d (4 replies)

Thank you, and dammit. This could be it

zeppo@lemmy.world · 3 pts · 13d (3 replies)

From your description, quite likely. I dealt with those in houseplants for a decade. They're not nearly as destructive as aphids, for instance, but they're a pain. One time I squeezed a plastic pot that had a plant in it and the larval stage reared its head out of the soil like a sandworm in Dune☠️🪱

solo@slrpnk.net · 1 pts · 5d (2 replies)

Update: You have no idea how hard I looked for BTi, I only found a 20kg powder that would cost over 600€. Also, I did not find a biological alternative. So, today I decided to give up on the search. And btw I managed to catch one of the gnats, so I am 99,9% certain that they are what you suggested.

In the mean time, the gnats are multiplying. So, I was thinking of isolating the 2 grow bags for starters, but I don't have enough room for this. Would covering the top surface of the soil with 2cm (0.75 inch) or so of sand be ok as a temporary fix for isolation? Or they can manage to get out of the grow bag?

What can I do with this amount of soil to make it usable again at some point? It's a lot, 60lt (15.85 gallons).

Once more, any idea is welcome!

Edit: I have the impression the sand thing is working pretty fine!!!

zeppo@lemmy.world · 1 pts · 5d (1 reply)

That’s odd. It’s really common and I can get some for $12.

By BTi, you mean Bacillus thuringiensis israelensis? Just get regular Bacillus thuringiensis.

solo@slrpnk.net · 1 pts · 4d

Bacillus thuringiensis kurstaki (BTk) is the one common here. It's also cheap, I found the 200ml for 4-5€. But it says it's for moths and butterflies.