Spiders are carnivores that prey on insects and other spiders. Spiders will eat almost anything they can catch, including flies, mosquitoes, cockroaches, bedbugs, crickets and moths.
Spiders populate where there is a good food source. If no food source is available, the spider will leave. That's why it's important to control pests and insects in the home to avoid a spider infestation.
Raising a house spider as a pet, or using it for short-term observation, requires catching insects outside or purchasing food like crickets to feed the spider. Spiders also need a water source and will drink from a small, shallow dish or from water misted onto the web.