Do you have critters in the terrarium? If not, I don't see why not. It will film up the sides of the glass and you will have to wash that off.

Larry

I do not have any pet critters just the wiggley dreadfuls that are noshing happily on my plants. I did spray the soap mixture so time will soon tell, I guess.

You could have also sprayed with Bt (Bacteria thuringiensis)

Yep! I would have used BT.