Of the spider species commonly found in homes in Nebraska, both in rural areas and in cities such as Omaha, most are entirely harmless to humans. Two species that often take up residence inside homes are cause for some concern.

Common House Spider

The common house spider (Achaearanea tepidariorum) is very abundant throughout the United States, and it often coexists with humans inside houses. The species' abdomen is usually gray, brown or yellow, and its legs are typically yellow with darker bands. Females have a body length of about 1/4 to 1/3 inch, and males have a body length of less than 1/4 inch.

These spiders tend to build their webs in corners and where edges meet, such as at the junction of walls and ceilings and in window frames.

Cellar Spider

The longbodied cellar spider (Pholcus phalangioides), like the house spider, is one of the most common spiders in the United States. The species' body color is very pale, usually tan or yellow, and it has a small gray marking on its back. Females have a body length of 1/4 to 1/3 inch, and males have a body length of about 1/4 inch. The spiders have extremely long forelegs which, in females, can reach a length of almost 2 inches.

These spiders prefer damp, dark, secluded spots, and they build their webs in cellars, garages and other out-of-the-way places.

Potentially Dangerous Spiders

Two species of spider commonly found in Nebraska homes are potentially dangerous to humans. Although rarely a life-threatening danger to healthy adults, the venom of the black widow and the brown recluse can cause serious health problems in sensitive individuals.

Female black widows (Latrodectus mactans) are about 1/2 inch in body length, and their bodies are shiny black with an red or orange hourglass-shaped marking on the underside of their abdomens. Males are about half the size of females and have a banded or spotted yellow-brown coloring. Females build their webs in places where activity is minimal, and they rarely leave their webs and the egg sacs within it.

The brown recluse (Loxosceles reclusa) is a medium-sized spider with a body length between 1/4 and 1/2 inch. It's usually medium brown in color, and it often has a violin-shaped marking on the back of its head. The species avoids human activity, and in homes, it usually lurks in secluded places such as closets, attics and basements.