wrote in message
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The U shaped bulb in my bug zapper is a blacklight bulb. I cant find
replacement bulbs locally. To mail order one will cost me around $34.
I'm not willing to pay that much, particularly since the zapper only
seems to kill moths and night bugs which are not a real problem anyhow.
I hung it to hopefully kill flies. I'm not saying it's worthless, but
it's not worth $34 for a bulb which will probably only last a year.

However, I have not yet ripped the thing apart, but I'm assuming it's
made with some sort of transformer to create the high voltage in the
screening around the bulb. Then there's this florescent blacklight bulb
with associated ballast.

If this is the case, why must the bulb be blacklight anyhow? Why cant I
just wire a common lightbulb socket in the fixture and put a small CFL
bulb inside the unit? After all, my white porch light brings in bugs
like crazy. Why not use a plain CFL to attract the bugs?

And, if there is some important reason that it must be blacklight,
Walmart sells a blacklight CFL bulb for $7 or $8. That much I'll pay.

My question is why they use blacklight bulbs when a plain white bulb
draws bugs?

There are two kinds of bugs - day fliers and night fliers. The bug zappers
are designed to attract night fliers and then electrocute them. The UV bulb
appears bright to night fliers and so they are attracted to it. Day fliers
see UV bulbs as dim just the way people do. House flies are day fliers.

Any other kind of bulb than UV appears less bright to night fliers; but
white light from CFLs has some attraction because it has a lot of blue.
Incandescent bulbs not so much. The yellow so-called "bug lights" are
virtually invisible to night fliers.

House flies and mosquitoes don't respond strongly to light. House flies
respond to odors and mosquitoes are attracted by carbon dioxide exhaled from
breathing animals, including people.

So, the trick is to figure out what kind of bugs you want to attract and
where you want to attract them to and that's about all you can do.

Tomsic