Female Black Widows are famous for their toxic venom. Males, however, lack such a weapon and are not really known to bite. Even immature females do not have the power to poison a human yet.
Females have the trademark red 'hourglass' on the bottom of the round abdomen ("belly"). Males change in color and pattern as they mature, but are always smaller in size (about half the size) compared to the female. Females are known to eat the male after mating, earning them the name 'widow'. Females can store the sperm from a mating and use it to produce subsequent batches of eggs, long after the male is dead. Lifespans for females range from one to three years; males may live about two months.
The bodies of both genders are shiny and hairless. Juveniles can start out brown, white and orange, growing more black as they age.
Webs are irregular in shape, but strong, and are built under stones, near openings of rodent holes and on outbuildings such as sheds, outhouses or barns. They are unlikely to leave their webs and do not go out of their way to bite humans. Females guarding eggs will be more inclined to attack and bite instead of attempt to escape from a perceived threat.
The venom in adult females is highly poisonous to humans and REQUIRES MEDICAL ATTENTION. Some people feel the bite (like a pin-prick), others do not. Pain will eventually begin at the site of the bite and then it spreads to the stomach and back with cramping in the first 8-12 hours of the bite. Other symptoms also may include: sweating, nausea, tremors, restlessness, fever and headache.
If you suspect you have been bitten by a Black Widow, try to capture and/or kill the spider for proper identification at a doctor's office. If you cannot, don't fret. Do not attempt to suck out the venom. Immediately wash the bite area with soap and water. Put ice the bite site and elevate that body part. The Mayo Clinic recommends tying a tourniquet above the bite if on an appendage to help slow the spread of the venom. Seek medical attention immediately. Though it is rare for humans to die from a Black Widow bite because victims eventually get medical help, early treatment can reduce pain and illness and quicken healing. This may include taking antivenin and other medications. Those with heart conditions may even need hospitalization. Every human body is different. It is essential to let a medical professional treat this kind of bite.
Common name: Black Widow
Scientific Name: Latrodectus mactans
Other Names: Black Widow
Adult Size (Length): 3mm to 10mm (0.12in to 0.39in) COMPARE
Identifying Colors: white, red, black, orange, brown, yellow, white
General Description: shiny, pattern, hourglass, widow, biting, venomous, harmful
North American Reach (Though Not Limited To*): Alabama; Alaska; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Hawaii; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Virginia; Washington; West Virginia; Wisconsin; Wyoming; Mexico
* Keep in mind that insect reach is not governed by lines on a map and therefore may appear in areas/regions/states beyond those listed above.