All green fingers out there... Small flies living in compost? Attacking plants?

Bit of an odd one this, but here goes:





I re-potted my Aloe Vera plant, and a few indoor cacti just before Christmas, and since it has gotten a little warmer, I've started noticing small 'flies' hanging around the plants base, they don't appear to be affecting the plants in any way, I'm just worried that they might grow into something else, start laying eggs, increase in number or size etc. I feel they might have been living in the compost as I kept it outside...





Has anyone else encountered this before? What should I do about the plants - should I buy a different compost and re-pot the whole lot? Will it damage the plants being re-potted too many times?





Sorry I'm asking so many questions, but the flies are begining to bother me.





Pest sprays or insectasides maybe?





Only sensible answers, thanks.

All green fingers out there... Small flies living in compost? Attacking plants?
We had this exact thing. It affected every plant we repotted, and then the flies spread to other house plants. They are a specific kind of gnats (forget the name), also called fruit flies. Unfortunately, they lay eggs in the soil. There is a product called Gnatrol (expensive) that contains bacteria or protozoa or something that attack the eggs in the soil, but it doesn't work well. In the end, we had to throw all the house plants away to get the flies out of the house, and never use soil from the same source again.





I remember now, they are called fungus gnats.





One more addition. Using insecticide will kill the flies that you can see. But it will do nothing at all to kill the eggs in the soil. You cannot get rid of these things with insecticide.
Reply:They're probably fungus gnats. They live in compost and potting soil and their larvae feed off of bacteria and fungus in your compost. You might try a little insecticide (crystals) on top of your soil and then water. It might help.





Your Aloe is probably not going to be good for medicinal purposes after that, though.





Sorry, not great news.
Reply:Yup, i have encountered this several times, using the same cheap compost!. So, when i repotted, i went for the more expensive reliable compost, and hey presto, no more lil pests!. It did cost more money and i had to throw away a few of the plants, but some of them i saved. The lil fly things are a nuisance and hard to get rid of if you keep the plant. Before re-potting, check the roots, thoroughly but gently for any more "flies". They are the same type you get if you have some rotten potatoes you'd forgotten about(hands up, guilty of that one, lol). Try not to repot your plants to often though, so place them in a larger pot. Hope this helps.
Reply:i also have had the same problem this winter in my greenhouse, I've been using seven, an insecticide, i got at the hardware store. it does not harm plants, you can even use it on animals, for like fleas and such. its been working pretty well. give it a try!