I checked the thermocell out myself and imo it' s fine for cookouts and fishing but the ones i' ve seen made a noise and i wouldn' t use it when hunting. It wasn' t real loud but it was loud enough that the deer in my neck of the woods would hear it and probably anywhere else especially on those nice calm afternoons or mornings.

I have to edit my post, i made a mistake the unit i was talking about wasn' t a thermacell it was something else. Ijimmy is right I talked with the folks at thermacell and they assured me that it is silent and odrless. I' ve been using a Shannon bug tamer but i may just have to give the thermacell a try this fall and see for myself how well it works.