It gives off a very powerful spark to even the smallest of bugs. You can hear it when a bug flies into it...pop-crackle--bzzz!  I bought it to lessen our chances of getting bit by mosquitos that carry the zika virus, or other mosquito-borne diseases. It has a fluorescent lamp inside that attracts bugs. I just don't know where I can get a replacement bulb for it, when it goes out.