There are approximately 2,500 different types of spiders in North America. Most spiders are not house dwellers, instead preferring an outdoor habitat. However, a few do enjoy dark places like basements, and they eventually find their way into the rest of the house.
Jumping spiders sometimes find their way inside during cold weather. They stalk and jump on their prey rather than waiting in the web like other spiders. Occasionally this spider bites if provoked, but the bite is not dangerous. They have the best eyesight of all spiders.
Common House Spider
The common house spider is the one that leaves cobwebs in the corners of a room, usually on the ceilings. It is extremely rare for them to bite, and there are no complications, like lesions or blisters, if they do. They are not poisonous.
Long-legged cellar spider
The long-legged cellar spider is also known as the daddy long leg spider. It can be found worldwide. Inside a home, it is found in corners hanging from the underside of the web. When threatened it has the ability to vibrate rapidly as a show of defence, but any claim that this spider is poisonous is a myth. In fact, bites from this spider are almost unheard of.
The brown recluse spider is a traveller, meaning that it often hides in boxes or bags and can be carried into homes. It is active at night and hides in the folds of clothing or blankets. The bite of the brown recluse injects toxic venom. Suspicion of a brown recluse bite should always be followed up by seeing a doctor within 24 to 48 hours.
Sac spiders do not weave webs like other spiders. Instead they seek a retreat. Outside, curled leaves, among other things, are home to sac spiders. Inside, they seek areas to hide and retreat, including high ceiling corners. Sac spider bites are painful and can mimic a brown recluse's bite's ulcerated sores. But they are not as dangerous as the brown recluse. Antibiotics might be needed to prevent infection.