Unfortunately, the solar-powered bug-zappers have hardware reliability problems. Last year, I managed keep three of the original four operational all summer. This year, I could revive only one. The other three are stacked in the corner of the garage waiting repair. Last year, the failure point was a cheaply-made switch that I managed to jiggle enough keep working. This year, I'll modify the circuitry to bypass the switch, and maybe I'll have to change a few batteries.
The zappers aren't that expensive. The ones I have are no longer available, but Amazon lists a pair for $25. I considered buying, but when I checked the bad reviews for them, I decided it was time to upgrade the experiment. We now have a grid-powered bug-zapper that's supposed to provide protection over a one acre area.
Several of the reviewers expressed disappointment over the ineffectiveness of the zappers for mosquitoes. This is no surprise, since mosquitoes aren't moths and aren't attracted to lights. They use their sense of smell to find victims. Most bug-zappers these days come with a mosquito-attractant pheromone that requires monthly renewing to be effective. Since a pheromone attachment came with the zapper I bought, I installed it, but I have to question its effectiveness in windy situations. It could actually make matters worse.
It recently occurred to me that I have another moth situation around the yard where a bug-zapper might be useful. Every summer the hornworm caterpillars harvest the new growth of our tomato plants.
They can be controlled with malathion and/or Sevin spray, which I don't like using, or one can go early each morning before it gets hot and pick off the worms. Being a lazy gardner, I'm not successful at the latter method.
I learned that these colorful and destructive worms are part of a nocturnal moth's life-cycle. According to my The Audubon Society Field Guide to North American Insects and Spiders, the Tomato Hornworm Moth and the Tobacco Hornworm Moth (we get both) have four-inch wingspan, a bit much for my solar bug zappers, but I've moved my last working one to the garden. Maybe I'll get lucky.