Those flies are the biggest pain in my backside. I don't care if I spot clean daily, somehow they end up in my snake room. I swear I don't know where they come from or how they get there. I may try everything that comes up in this post.
Also, they are worse in different cages depending on substrate. Mulch -- they're everywhere, Cypress -- any uncleaned spot they're all over, Paper towels same as cypress, BUT, in my arboreal cages where I use absorbent bed pads because I mist and the snakes stay off the ground, I don't get them at all, even on dirty spots.
Hate these things.
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Brian Suter
www.serpenteer.com