A question we all ask at some point when keeping isopods is "what are the flying things in my isopod enclosure?" or "how do I get rid of the flying things in my tanks?".
Over the course of keeping isopods for around 5 years now, I have had issues with fungus gnats a few times. It is almost impossible to never have an issue at some point with these critters as they are attracted to the same conditions that isopods thrive in — high humidity, decomposing organic matter, and most soil and substrate.
The adult gnats are drawn in by the humid environment to lay their eggs, then the larvae (babies) feed on the leftover isopod food and decaying plant matter.
It may not seem like much when you see a few gnats but considering that females lay anywhere between 10-40 eggs every 7-10 days (laying up to 300 eggs in a lifetime), it is important to remove/destroy the gnats as you see them as well as removing areas of larvae where possible. Especially given that adult fungus gnats (flying stage) lay eggs within 1-2 days of emerging from the pupae stage.
After trying many ways to resolve this issue over the years including drying enclosures up, free standing fly zappers, and fly paper hanging from light fittings, I wanted to share with you all the way that I got rid of my last outbreak very quickly and then keep it manageable now very easily.
The Method That Actually Works
The only thing you need to buy here is an electric fly swatter which is rechargeable — this is the one I purchased: https://www.amazon.co.uk/dp/B0DLK3MDKD. These are relatively cheap and given they are rechargeable you don't even have to replace batteries.
Once your swatter arrives, I used mine right out of the box — it came with almost full charge which was ideal. What I did was open a tub of isopods that was affected and turn the swatter on and rest it over the top of the tub, ideally in low light. The gnats will swarm to it and you will hear a zapping noise every time a fly is hit (killed).
One question you may have here now is "will this not electrocute my isopods?" — short answer NO it won't. The reason being, fungus gnats don't hold an electric charge, therefore as soon as they leave the swatter they are safe for the isopods to eat.
Once you have left the swatter and there are no more zapping noises, tap the tub — this usually encourages the remaining fungus gnats to move. Once this stops, move onto the next tub until you are done, then sit this swatter on the stand/holder supplied and leave it in the room near the tubs. It is best to do this when the room is dark if possible — you can also charge the swatter via the stand too.
You want to repeat this once a week until you are no longer hearing any zapping noises. Then going forward keep this swatter by you when doing isopod maintenance just in case — once every few weeks.
Why This Works So Well — The Isopod Connection
One of the reasons fungus gnats lay so many eggs so often is they have a lot of predators in the wild — one of which you wouldn't believe are isopods! So by killing off the adults you are helping disrupt the breeding/lifecycle and then the isopods will help get rid of the rest. The smaller isopods usually eat the larvae if they come across them, however larger, more protein-hungry isopods are more likely to actively hunt and eat the soft-bodied larvae. Isopods may also eat the eggs if they come across them too.
Just be aware: fungus gnats are different from springtails (which you actually want in your tubs as bioactive cleanup crew) — gnats fly and look like tiny mosquitoes, while springtails are wingless and tend to stay on the substrate surface.
The Fungus Gnat Lifecycle
The complete lifecycle is pretty quick, being around 3-4 weeks in optimal conditions (around 24-27°C and high humidity). So although you notice they come about very quick, don't worry — the breeding cycle is quite easy to disrupt.
- Eggs hatch in 4-6 days
- Larval stage lasts about 2-3 weeks (they go through 4 larval instars/sheds)
- Pupal stage lasts 3-5 days
- Adults emerge ready to mate and can begin laying eggs within 1-2 days
Properly worth getting on top of it early — the maths means a small problem becomes a big problem fast if left alone. But with the swatter approach plus letting your isopods do their natural predator work, it stays manageable. Browse our accessories collection if you want to ensure your substrate components aren't already arriving with potential gnat eggs (good practice is to bake substrate before use if you're concerned).
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