Pest Identification

Learn More About the Pests Invading Your Home

What You Need to Know About Black Widow Spiders

Black widow spiders are venomous arachnids and are part of the Theridiidae family. There are roughly 30 species of widow spiders, including red widows and brown widows, but only five species in the United States. However, the black widow spider is the most common and well-known of the species, and is highly venomous making them important to know about.


How Do I Know What Black Widow Spiders Look Like?


Black widow spiders differ in appearance between males, females and juveniles. All feature a large bulbous abdomen that is sleek and shiny, and all have eight legs. They are usually black but can be brown as well. They are considered comb foot spiders, and have bristles located upon their hind legs that they use to silk their prey. Females can grow up to an inch and a half long, roughly twice the size of their male counterparts, although males have noticeably longer legs. They are known for the females having a red hourglass shape upon the underside of their abdomen, although the identifying mark can also be yellow to orange in color. Males can be identified because of their red or pink spots on the upper side of their abdomen or bands that are yellow or red in color. Juveniles are similar in appearance to males.


Do They Live Near Me?


Most black widow spiders live in the south, west and northeastern United States. They prefer to live in temperate areas, are most active in mild weather and are most commonly found in the southern area of the country. 


Where Do They Like to Nest?


Black widows are generally solitary animals and only come together to mate. They prefer dark and secluded areas and can be found in crevices or woodpiles and on the undersides of rocks, ledges and plants. They are web weavers and will produce a nonsymmetrical web near their home. Drought and colder weather may drive these spiders indoors. In buildings and homes they are typically found in garages, basements, closets and cluttered areas.


How Can I Keep Them Out of My Home?


Some steps to prevent black widows from inhabiting your home and yard include tidying up and preventing them from getting inside. Clear out debris from your yard and declutter your home and garage. Vacuum your home, paying special attention to corners and hidden areas. Look for webs and egg sacs while you clean and remember to dispose of your vacuum bag once you are done. Seal any holes or cracks you may find in your garage, barn or shed.


How Harmful Are Black Widows?


Black widow spiders are the most venomous spider in North America. However, they only bite to ward off a perceived attacker. It is only the females who pose a serious risk, and they are mostly dangerous only to those who are very old, very young or have underlying health conditions. For most who are bitten, the effects are generally moderate and include difficulty breathing, muscle aches, particularly in the abdomen and back, profuse sweating and nausea that may persist from a few hours to several days. Males and juveniles are not considered dangerous.