A bug fan will catch the moths around your house at the same time it is catching the mosquitoes. A light is not a large help for mosquitoes, as they fly around everywhere at night, and eventually get on the business end of your bug fan. But moths are highly attracted to light, and using one behind your bug fan at night will catch many times more than without it. More moths than you ever saw flying around during the day time. A black light seems to attract more moths than a white light, but any light is better than none.
Why would you want to kill moths, since they don’t bother us as mosquitoes, gnats, and other biting insects do? Well, their eggs turn into caterpillars, the same ones that are eating your garden. They have been known to eat clothes and blankets. Quoting from Wikipedia on this subject: “Caterpillars are voracious feeders and many of them are considered to be pest in agriculture. Many moth species are better known in their caterpillar stages because of the damage they cause to fruits and other agricultural produce.”
If you do not want to spray chemicals in your garden, then the next best thing is to be able to reduce the problem to start with. Killing as many moths as you can around your yard, will reduce the caterpillars you see boring in your squash and cucumbers, and eating the leafs of your other plants. Breaking the breeding cycle gives long term reductions of any insect. To be the most effective, you should start in the Spring even before you have noticed any. Get the first ones who come around, and then keep killing the others that will be flying in all season long. Nothing, even poison sprays, will kill everything forever, but every moth in your net today is one that is not laying eggs tomorrow.
A Bug Zapper will attract more moths then it will ever kill, because they like to just land on the outside of it, sit around and look at the light. Every now and then a moth will make it the electric grid, and get fried for several seconds accompanied by some smoke usually. When they try to get close to a light hanging off the back of your bug fan, they are gone.
You are limited to how big a moth you will catch by the size of the grill on your fan. Moths that are too big to go through the grill will frequently get stuck in it, and dry out. Those you have to get a brush to clean off, while the smaller ones which end up in the net, you just dump out. When you buy a fan to make into a bug fan, pick one with the largest spaces in the grill so larger moths and other insects can get through it to the net. Due to product liability, these spaces have gotten much smaller than in the past, but with most fans you can easily modify the grill by making larger spaces. Just be careful with small children of course, but a pedestal fan will usually be high enough off the ground that you shouldn’t have to worry about it.
Using your bug fan to kill moths as well as mosquitoes may be a new idea, but it is one that you can actually see the results, every morning in the net.