Common Invasive Spiders
Common Names: house spiders, wolf spiders, cellar spiders, jumping spiders
Scientific Names: Latrodectus species/Loxosceles species
Spiders are arthropods that belong to the class Arachnida and order Araneae. Spiders have two body regions (unlike insects, which have three): the cephalothorax (head fused with thorax) and abdomen (sac-like and unsegmented). Spiders have 8 legs (unlike insects, which have 6), a pair of jaws (chelicerae), a pair of feeler-like pedipalps, one on either side of the jaws and either 8 eyes or, less commonly, 6 eyes. All spiders are predators and produce venom with which they subdue their prey and defend themselves. Over 37,000 species of spiders occur worldwide, including over 3,000 species in Europe and about 3,600 species in the United States and Canada.
Relatively few families of spiders commonly enter human structures in the Midwest and those that do are usually not considered to be dangerous. Representative species of the five most commonly-encountered indoor (structure-invading) spider families are discussed here.