What is the best spider killer spray?

No pesticide spray is recommended to control or kill spiders. Biologically they are not very vulnerable to chemical insecticides because they aren't true insects; they're arachnids. Spraying isn't effective unless one makes a direct hit on the spider.

Since they walk on long legs, insecticide residue on the surface only touches their feet, but spiders lack a circulatory system that will take the insecticide to the internal organs to cause a quick death. The most effective spider control involves swatting it with a newspaper, a shoe or some other weapon. It's also helpful to remove their prey, such as other insects, from the environment.