I've used Safer Soap on my ficus (that died...not from that though) when I had all kinds of aphids...but I wouldn't want to use that stuff in a vivarium! At least remove the plants, and rinse them REALLY well before they're replaced...but it's not a good idea to use that stuff with animals.
How big are these bugs? I've got springtails in some plants...they're hard to see and when they jump they appear to disappear. They're not a big deal. They're actually beneficial.
What makes you think they're mosquitos?
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