Thank you for an interesting topic today.
Here is the information about "electronic" mosquito coil.
I learn a lot about mosquite bites today:
Katori-senko is made by hardening pyrethrum, which contains a mosquito-repellent ingredient, into a flat spiral coil. It is usually burned on an unglazed porcelain dish in a room. The smoke from the katori-senko drives the mosquitoes away. It is still used by many people because the smoke has been proved to be harmless to people. Lately, however, an electric appliance which emits mosquito-repellent gas using chemicals has come into wide use and this appliance is used much more than the conventional katori-senko.
