Insects Found in Plant & Succulent Soil Mixes

I don’t know if this question is really relevant, but I’m going to ask anyway. I use a cacti and succulent soil mix, and sometimes when a few pieces of soil get on the floor, I find insects in the mix. They are so tiny, that they might as well be microscopic. I’ve tried taking pictures, but my cameras cannot get details of something that little.
I often find tiny flies near non-succulent plants that look very similar (and may be related) to the insects I found, so I think those insects are also found in non-succulent soil mixes. I was wondering if these insects are normal and perhaps beneficial to the plants. I also (if possible) want to know why they’re in the soil and why they’re so attracted to the plants.

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They’re probably springtails, which are vital to the soil cycle. Also, not technically insects, although they are closely related.


Do they fly? Dark-winged fungus gnats are often found in soil mixes.


Yes, they do fly.

If they are fungus gnats, often found in soil and compost, they are not good for your plants. Their larvae eat the tiny roots off of seedlings (in addition to fungi, as their name suggests), causing them to die so they are a common problem in seedling flats. I think yellow sticky cards are commonly used to catch the adults in greenhouses for monitoring and control. Another way to control them is by removing standing water and letting the soil dry out completely between waterings, as the larvae prefer moist soils. Adults may emerge in a wave after previously dry soil is watered again, so that might be a good time for putting up a sticky trap near the pots that have them.

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I have battled many a fungus gnat infestation, and this is good advice. One preventative measure is microwaving soil mix before using it. You can often see fungus gnats come out when a bag is opened or crawling on the surface. I make my own sticky traps by putting Tanglefoot on any yellow carboard/paperboard that would otherwise have gone into the trach. If you get gnats on the sticky trap, it will be easy to take a pic to upload to iNat where it could be IDed.

You can also bottom water and place diatomaceous earth on the top of the soil which will kill many gnats. Another solution is to but predatory nematodes that you put into water and then water the plants with. A bit pricier, but works well.

Is it possible for a potted plant with the right soil mixture to be home to a dormant Cicada? I know they hibernate for many years under the soil as grubs while eating decaying matter, but don’t know how finickey they are about the sites they choose

I have a potted Gasteria/Haworthia-type hybrid succulent which had a fungus gnat mini-population recently. At first I had no idea what they were. I decided to move the plant closer to the floor-to-ceiling windows that my flat has. A few hours later, I noticed a few ants crawling around the pot, with one carrying away one of the fungus gnats. I left the pot there for a few days and the ants hung around until the fungus gnats disappeared.

I think it was a combination of the heat of the sun drying out the soil and the ants’ predation that resolved this from becoming an infestation. It was very interesting for me to observe!