I've got an Exo-terra terrarium that I'm currently keeping my grey tree frogs in, and it came with a stock foam background, like most or all of their terrariums do, but I've noticed recently that the crickets I've been putting in for them to eat have been chewing on the top rim of that foam background.

I've been doing my best to take out excess crickets during the day so they won't do so as much, and I've always kept something for them to munch on inside the enclosure, usually some kale leaves or bits of other veggies, but I can't get them all, and I can't watch the tank 24/7 to shoo away or take out every single cricket that wanders up there - and given that they're photophilic, it seems like all they're interested in doing is just that.

My question is, how dangerous could this possibly be to the frogs' health? I'm sure the foam is "non-toxic" but I'm also sure it's not intended to be ingested, second-hand or otherwise. Any feedback is greatly appreciated, because this is really bugging me, and to remove that background would require a total disassembly of their house, and I don't have any other open terrariums at the moment to transfer them to in order to do so.