I've used bug zappers for years, I don't let them burn 24/7 and have learned that I can disrupt the breeding of some insects by using it for three days a month, a couple months out of the year. They are indiscriminate killers and will take out many beneficial bugs when used incorrectly. Once you learn when to turn them on,  or notice a hatch of gnats they work well. They will not attract blood suckers without bait. I've found that cash works best, sorry bad joke. For blood suckers there are better environmental options but nothing in this price range.