Seed Swaps

loads of tiny flies what are they?

I have all my little seedlings started indoors. Over the past 2 weeks I have noticed more and more of these tiny little flies. They are too small for me to get a picture of but they start off as really tiny, white, kind of wormish things then turn black and develop wings. There are literally hundreds of them all over my house. I have put double sided sticky tape around my pots today to see if I can trap them on that but apart from squishing any that I see I don’t know what else to do. Any suggestions as to what they are, where they came from and how to get rid of them?

Posted over 3 years ago

sounds like fungus gnats. I know to avoid getting them, you dont want the soil surface to be constantly wet. My other technique is to always have a fan going lightly on the seedlings. I’d love to hear ideas about getting rid of them.

Posted over 3 years ago

I think anelson is right and the advice given is sound.

I am having the same problem. Not 100’s but enough that I am annoyed by them.

I learned from a fellow folian last year that if you put a layer of sand on top of the soil, they won’t be able to emerge from the soil. I do this with my houseplants and this method shouldn’t harm seedlings.

A few things I have read but not tried are neem oil, insecticidal soap and a dish with apple cider vinegar that you put plastic wrap over and poke holes in.

How is the sticky tape working? I was thinking of trying that next. I have a few bowls of vinegar out now (not apple cider, I just had regular, but I put a splash of juice in it)

Oh, another thing I read that if you have a really big problem, to close the lid on your toilet and not have any standing water anywhere (tubs and sinks) because they are attracted to the water.

Good luck!

Posted over 3 years ago | Last edited over 3 years ago

I think anelsom is right too. I had this same problem (although not with my seedlings – with all my plants!) due to a bag of infested potting soil. The gnats larvae live in the soil and eventually emerge as the fliers. If the problem is throughout the soil you may not be able to eliminate them. I don’t think they hurt your plants – they’re just really annoying and they will infect every plant you have if not eliminated quickly. For a small infestation I used a solution of dishwashing liquid (one tablespoon) diluted in about one litre of water (standard spray bottle) and sprayed the surface of the soil lightly to kill off the existing fliers and the larvae. Also as Deanna said, don’t keep the surface of the soil wet as that will attract them. The sand is a good trick to try. The soapy water worked for a small infestation but if the problem is rampant (ie: deep into the soil in multiple plants) you may have to transplant seedlings and established plants into fresh soil and get rid of all the infected soil. It’s a pain and I had to do it but it worked. Just remember that if you need to do that, be sure to wash the plants and the roots really well – don’t keep a clump of soil around the roots or you won’t eliminate the problem. Note that you may end up losing some plants.
The vinegar trick won’t work – that trick is for fruit flies – and these are not fruit flies.
Sorry to be the bearer of bad news but I’ve been through it so I know what you’re dealing with. Good luck.

Posted over 3 years ago

I have loads of the little flies as well and purchased these which catch an inordinate amount of them. Works really well for me.

Posted over 3 years ago

Thank you all so much!
anelson – fungus gnats sounds gross!! lol like something someone would get on their feet!! LOL! but yes, I do tend to keep my soil so that it is moist – wet on top because my house is so warm the soil dries out really easily. I have had a couple of my little pots which have teeny weeny mushroom looking things on the top of the soil, I thought these may be eggs or larvae or whatever so I just got rid of the whole pot straight away. Thank you

Deanna – I think I will try your sand method and ensure the toilets are closed and sinks etc. are drained. I only just put the sticky tape on today and now that you have asked, I am going to check………nope, nothing on there. Wait a minute, I am gonna shake em up and see what happens back in a mo! lol ……… shook and blew on them they all flew around and then straight back to the leaves or the soil completely missing the tape :((( grrr!

charlie23 – That is exactly what I thought! The soil was infested when I bought it! I really hope I don’t have to go through the re-potting/washing cycle, I have way too many seedlings and sooooo not enough time for that (although I will if I need to! lol) Thank you

crochetkim – I have bought the brilliant little things before for midges – which are in abundance here in Scotland – and they do work brilliantly. These are where I got the idea for the double sided tape from which unfortunately doesn’t seem to be working :( Unless, maybe, it is not quite sticky enough….. Thank you

Thanks again everyone I will keep you updated on my progress with the little pests! lol

Posted over 3 years ago


Folia Helper

United States5b

I have had some fungus gnats in my seedlings and I have used Knock out Gnats™ granules, which is a biological control (Bacillus Thurengiensis H-14) that kills the larvae in the soil. It does not kill the adults, so you have to do a series of 3 applications 1 week apart to get them all. I have used sticky traps for the adults, but it didn’t snag all of them.

Posted over 3 years ago | Last edited over 3 years ago

Hi there! You're reading a conversation in the Kitchen Gardens group on Folia.