Virtually all Bug Zappers and Bug Traps use a black light bulb, or at least a purple light bulb, to attract insects to the machine. How effective are they? University studies have shown that the Zapper they tested killed very few female mosquitoes. Less than 2% of the dead insects were female mosquitoes. How they knew what fried critters were is a mystery, but these guys went to college for it.
My experience with Bug Zappers dates back to about 30 years. They would all be diving at night, but the mosquitoes were still biting me. When something that looked like a mosquito began to form a layer on the zapping grill, this layer expanded every night. I theorized that the dead insects stuck in the net were heating up and releasing CO2, drawing more mosquitoes to their deaths. It’s hard to tell what a dead fried bug is, but the ones sticking to the advertised non-stick grill certainly looked like mosquitoes. I have also observed moths and other non-biting insects attracted to black light, occasionally passing through the outside grill and frying. They were the ones who emitted the longest and loudest crackling sound and blew out a puff of smoke.
I put little faith in the University studies that said it wasn’t really killing so many biting mosquitoes. I also knew that to really reduce the mosquito population, I had to wait a few weeks for the ones I killed to break the breeding cycle long enough to make a noticeable difference. The problem with this kind of thinking is that the life cycle of a mosquito is only a couple of weeks. If you had a big mosquito blast, like after heavy rain, they will still disappear in a few weeks without doing anything, unless they are continually reproducing.
With an insect fan, you can view the actual insects you catch while you are still alive, making it easy to identify until they die and dry to dust. To test the efficiency of using a black light, I ran two identical bug fans, one with a black light attached to the back and one without. The black light used was a CFL bulb, it cost about $ 5, inserted into what is commonly called a “trouble light”, it cost about $ 15. The CFL bulb is curly compact fluorescent bulbs, which have a lifespan 10,000 hours or more. These are also made using older incandescent technology, which don’t perform as well, have a lifespan of maybe 1,000 hours, and use several times as much electricity. For comparison, a Zapper’s black light bulb is typically around $ 15-20 and rarely last a full season.
My results were surprising, if you thought that black lights attracted mosquitoes. I caught pretty much the same on both Bug Fans, with the unlit Bug Fan mostly catching mosquitoes. The insect fan with the black light caught many more times the amount of insects. Moths, mosquitoes, smaller black-type flies, tiny flying beetles, and other insects that I didn’t even know were flying around my porch ended up in the net every night. Now when the bugs are heavy I run a Bug Fan with a black light and the others without it. Every morning when I look at the nets, I know I’m making a dent in the mosquito population, because I can see the ones that flew onto my porch. I can also see the results when I sit outside. Mosquitoes, gnats, and other flying insects are greatly reduced or eliminated immediately, without waiting for their life cycle to end.
In conclusion, although a black light does not necessarily attract mosquitoes, it does not repel them either. It attracts most other flying insects, which is good, and makes Bug Zappers owners feel good about their purchase as they listen to it zap all night. Since none of these bugs would be considered beneficial, get a black light, get a Bug Fan, and remove the bugs.
