I went to Bunnings for a mosquito zapper. All the ones I could see had the Mosquito as one of the pests zapped.
When I asked which was best in store the assistant said none of them actually does the job.
Unfortunately, many biting bugs are not attracted to the UV light coming from bug zappers , mosquitoes and biting gnats included. Traditional bug zappers will kill a large number of harmless insects. In fact, they may even kill a larger number of beneficial insects than harmful ones.
With summer here, and humidity (in WA seeming to be on the increase; Ross River Virus, etc, if they don’t work, they shouldn’t say they do.