That is unheard of for me!! We camped a whole weekend, spending the majority of the day outside, and this thing rocked!!!To use it, there's a small bottle of butane you screw into the end of the unit

We have been using TheraCell products for many years and I highly recommend them

But I can tell you that it works great against what ever ones we have in south Florida

It puts off a little heat, and a little smoke and very little smell

We also got the lantern to use at home, and it works wonderfully also

The repellant is activated by a butane flame in the unit