They are similar in appearance to immature females. Widow spiders build loose and irregular mesh-type webs, often on plants, in loose stone or wood piles, or in the corners of rooms, garages or outbuildings. Eggs of widow spiders are laid in an egg sack, attached to the web of the mother. The sack is pear shaped, and creamy yellow, light gray, or light brown in color. About 200 eggs may be laid in an egg sack and females may produce several egg sacks if conditions are favorable.
Widow spiders prefer to nest near the ground, in dark, undisturbed areas.
Nest sites often are near holes produced by small animals, or around construction openings and wood piles. Low shrubs also are common sites for widows to occur. Indoors, widows similarly occur in dark, undisturbed sites such as behind furniture or under desks. Undisturbed basement areas and crawl spaces of homes are also used by nesting widow spiders. Muscle and chest pain or tightness are some of the most common reactions to the widow toxin.