Fungus Gnats
Get on top of them while the infestation is small.
Even in large numbers, it's not the adults you need to worry about, it's the larvae.
Fungus Gnats love warm, moist conditions. A bad infestation can continue right through winter, so you can't just wait it out. When Fungus Gnat larvae feed on your plant's roots it can stunt plant growth, particularly in seedlings, newly rooted cuttings and younger plants.
The secret is to break the cycle by targeting both larvae and adults at the same time.
You need 2 things: Sticky Traps and a Systemic Insecticide
Sticky traps are available online, or right her on our store, just look under Pest Control. Place them as instructed on the label.
Systemic Insecticides are great for most house plant pests, my go to is Grosafe Groventive, but you can choose whatever works best for you, just make sure that whichever product you choose targets the correct pest and that you use it as per the label instructions.