Worms in indoor hydroponics? Fungus gnat larvae? Drain flies?

For several months now, I have been noticing small, dark-colored insects flying around the house. They haven't multiplied to the point where I would call it a full-blown infestation, but they definitely have been noticeable and are somewhat of a nuisance if and when they fly around.


Just recently, while changing out nutrient solution for several lettuce plants did I notice a small, black line in the roots. At first, I assumed it was just a small root that had died, but upon closer inspection, I noticed it started to move and wriggle! Somewhat disturbed, I grabbed some tweezers and isolated these little worm-looking things to take a better look.

I did some digging and concluded that these are likely fungus gnat larvae or drain flies (AKA moth flies) that were feeding on the roots and nutrient solution. It also helped connect the dots with remembering the black insects flying around, which I naturally concluded were the fungus gnats or drain flies themselves. Interestingly, I've only found them on lettuce and mizuna roots.

It's somewhat unnerving at first because you don't expect any insect infestations in your indoor hydroponics system, but of course it's not a perfectly sealed system and pests can still come in. If you think about regular soil and how worms are almost a necessity for soil health, this puts things into perspective.

Luckily, the infestations have been kept to a minimum and there hasn't been any noticeable effect on the plants. I haven't needed to resort to any pest control measures but am hopeful that with regular nutrient solution changes, any eggs and larvae are flushed out as well.

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