Insects and the Home
Spiders can be hugely beneficial to the natural ecosystem around your home due because they prey on problematic insects. But spiders such as the brown recluse and black widow are dangerous to humans, so their presence requires immediate action. Insects such as ants and cockroaches can be a sanitation hazard while bees and wasps can present serious, potentially fatal risks to those with allergies. Even if the insects around your home do not present a risk, you may want to remove them simply for cosmetic reasons.
Spray control of spiders can be tricky since insecticide sprays are only effective when they come in direct contact with the spiders. Still, any insecticide containing pyrethrins, resmethrin or allethrin can be used to kill spiders on contact. Other insects can also be controlled with insecticidal sprays; simply purchase ones that are rated to kill the specific insects infesting your home. Always follow the application instructions carefully and use the smallest amount of insecticide possible.
Alternative Control Methods
Most experts recommend spray pesticides as a last resort. Not only are most of the chemicals used toxic to humans, but spraying can leave toxic residue on beneficial plants and insects that you don't intend to kill. Overuse of spray insecticides can also contaminate ground water and soil if not disposed of properly. Consider tamper-resistant bait boxes, insecticidal soaps or non-insecticide chemicals such as boric acid powder as alternatives to spray control.
If you're certain that you need to use chemicals, consider hiring a professional exterminator. They are trained in the handling, application and disposal of insecticidal chemicals and know how to limit human exposure.