September 09, 2010

Q: How dangerous are spiders to humans? Should I be scared about the spiders in my house?

The Burke Museum partners with the Seattle PI's Big Blog to answer commonly asked questions about the natural and cultural history of our region. Read past entries from the Ask the Burke column here.

The following was posted to the Seattle PI's Ask the Burke column on September 8.

Q: How dangerous are spiders to humans? Should I be scared of the spiders in my house?

A: House spiders prey on insects and other small creatures. They are not bloodsuckers and have no reason to bite a human or any other animal too large for them to eat. In any interaction between spiders and larger creatures like humans, the spiders are typically the ones to suffer.

Although almost all spiders are venomous, very, very few spider species have venom that can harm humans, dogs, or cats. The purpose of spider venom is to subdue the spider's prey, almost always insects. In brief, it's an insecticide. Spider venom does not exist to harm creatures, like humans, which are too large for spiders to eat, and in nearly all cases has little if any effect on humans.

A minority of spider species have venom that can cause localized pain in humans, like the venom of bees or wasps. Of around 50,000 spider species known, only about 25have venom capable of causing illness to humans. These species are called "medically significant" spiders. In most parts of the world, such as the Puget Sound area, no spiders with medically significant venom have much chance of being found in houses.

To find the answers to more frequently asked questions about spiders, visit our Spider Myths website.

Interested in spiders and insects? Come to Bug Blast at the Burke on Sunday, September 19!