For years now, I've been buying "bug zappers" - you know, they have a blacklight and a charged grid that attracts and electrocutes insects. Trouble is, they're cheaply made and the light fixture part always fails after about a year.
So when the current one failed, I decided to take it apart and see what I could do. The whole thing consists of a dual transformer (120vAC to HVAC for the charged grid, 120vAC to 2.5vAC for the light.) and a small board with a photocell and an indicator LED. The leads for the light were just sitting in their sockets, not soldered or even clamped. I could have just attached the leads securely to the socket and it would probably have lasted awhile longer, but while I had it apart I thought I would switch out the fluorescent lamp for an LED array.
I used 10 400nm UV LEDS soldered onto a small breadboard, connected to the 2.5v AC side of the transformer through a 4A 400V full-wave bridge rectifier. I glued the breadboard to the case where the socket was, put everything back together, and now it works great. The LEDS are rated for 3v, so 2.5v should be no problem.
Now it looks great, but I don't know if the 400nm wavelength of light will work for mosquitos. According to my research, mosquitos are attracted to wavelengths between 370nm and 374nm. I guess I'll check it in a week and see if anything has happened.