1. Fly-catching artifact.

2. Fly exterminator.

3. Fly killer.

4. The most effective tool to kill flies is triangular.

1. The most effective tool to kill flies is insecticide. It is easy to kill flies effectively and quickly by using insecticides, but insecticides are generally some chemicals, which may be harmful to the body.

2. If you don't want to use pesticides, you can buy some fly-sticky paper, and put it on the desktop at home to stick the staying flies.

3. This way, the effect of killing flies is quick and the cost is low.