The only time that Dubia smell is when you mess with them and they let off this not quite unbearable but definitely not good smelling fluid. Other than that the only smell that I notice from them is when fruits or vegetables are left in overnight and get heated up from sitting right over the heat pad. I'd estimate my colony to conservatively house at least several thousand mixed sizes currently and the only time that I can really smell them is when I clean out the tub and get them all stirred up. They beat the hell out of crickets any day. When my monitor was younger I had to get 1,000 crickets a month and let me tell you, Those things smell like death.