Mix up the compost to disrupt their lifecycle.

Better yet, cover the stuff with a layer of browns.

In any event, fly larvae belong to nature's composting crew.

Hello: I posted here same problem before and mine is getting better with warm weather.Apparently they are lots of drain flies due to wet winter and spring. Not sure where you are? Anyways mixing is good and add brown leaves.They are doing their job just have not balanced situation.I sprayed soapy water , but it really is not helping much.Its not needed to spray.I know it looks like snowing when you disturb them right? Anyways good luck to you..

We had the clouds of tiny white flies last year. When I was consistent about covering new material with dried leaves, they weren't a problem anymore.

An update - Thanks for the suggestions - dry brown is the way to go! My compost is in a tumbler, so it gets tumbled regularly. I tried putting a thin layer of sawdust over the top after the tumble, and this seems to be working.

Please do let us know what exactly worked for you? I still have a bit of a problem but much less.The sun helps as it gets bit dryer.Let us know how much and what you added exactly to make an improvement.thanks

Wouldn't watering with a dissolved Mosquito dunk help?

Me the OP again. I'd be hesitant to use a mosquito dunk b/c of the worms and b/c I try to keep things organic (the compost gets used on my vegetable gardent).

Here's what I did exactly - tumbled the compost as usual. Then I scattered some old sawdust over the top so that there was a thin layer everywhere - just enough so that you couldn't make out the veggie peels, etc. underneath. I imagine that dried leaves, straw, or even dried mulch would work as well.

Thanks for that.Where do you get untreated sawdust? Also what wood was it from I was told cedar dust is not very good for composting.Thanks

Mosquito Dunks only kills fly and mosquito larvae, they do absolutely no harm to earthworms. Since all they contain are a naturally occuring bacterium they would also be considered organic. That being said, I'm glad sawdust helped the problem :-)

Oh! Thanks for the correction on the mosquito dunks. I'll look for them if the problem gets worse.

I inherited the sawdust as part of a plant exchange from a fellow gardener. One good source is probably folks who are getting stumps ground...

I am doing a science project and there are over a thousand little grey flies on the compost and spiderwebs.

HELP!!!!!!!!!!!!!!!!

One of the things you can use for browns is shredded paper, especially the cross-cut kind. Check out the compost forum on G/W for more info than you ever thought you would need! It's a great forum.