Most of the 20,000 species of spiders found in the United States are poisonous, but their fangs are too short or too fragile to break through human skin. The bites of most spiders cause only minor, local reactions, although a deadly reaction can occur.
In the United States, the two spiders that can cause serious problems are the black widow and the brown recluse spiders (sometimes called the violin spider). Both of these spiders are found in warm climates. If it is possible to kill or capture the spider without further harm to yourself or your child, it is important to do so. Place the spider in a glass jar or plastic container so it can be positively identified.