I've definitely never seen anything that looks like that. Are fungus gnats really a problem for frogs? I've had them on my plants for months and I refuse to spray for them. They don't really seem to bother anything or bite. They just like to hang out in the plants so why put harmful chemicals in my home? As I said, I have a bird so I have to be careful about that stuff. I'll only try to get rid of them if they're a problem. Otherwise, I'll consider them part of an ecosystem!