Wiktionary
n. An electrical discharge insect control device that attracts flying insects with ultraviolet light and electrocutes ("zaps") them with a high voltage.
Wikipedia
A bug zapper, more formally called an electrical discharge insect control system, electric insect killer or (insect) electrocutor trap, is a device that attracts and kills flying insects that are attracted by light. A light source attracts insects to an electrical grid, where they are electrocuted by touching two wires with a high voltage between them. The name comes from the characteristic onomatopoeic zap sound produced when an insect is electrocuted.
Usage examples of "bug zapper".
The bug zapper is the cheap microwave oven I bought a few weeks ago.
Maybe this was no more significant to them than the loss of a bug zapper in a front yard.
And now the bug zapper is down, we fly freely toward the house….
Thank God he didn't visit them as he visited Zuwayy in Jaghbub-with his bombers buzzing overhead destroying the place and wearing his medieval armor with the built-in bug zapper, Fazani thought.
There were sparks at the edges, like the blue fire of a bug zapper.
From down the road came the harsh electric sounds of a bug zapper instantaneously frying its victims.
Nothing in his life had prepared him for the sight of a dead rain forest, the skeletons of immense trees and vines with all the leaves blackened, dead animals covering the ground like a carpet, birds and lizards and small frogs, snakes and pigs, billions of insects like the bottom of a bug zapper.
During the day bees hovered, and at night moths and beetles died fast, brilliant deaths as they flew into the mesmerizing purple glow of the bug zapper.
It was a sweltering June night, hotter than a bug zapper on the fourth of July a white-trash cousin might say if there really was such a thing as a white-trash cousin.