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Black Widow (Latrodectus mactans)

Detailing the physical features, habits, territorial reach and other identifying qualities of the Black Widow.

 Updated: 8/2/2019; Authored By Staff Writer; Content ¬©

Sighting the small red hourglass shape on the belly of the glossy Black Widow calls for immediate caution and a plan of action.

Female Black Widows are famous for their toxic venom. Males lack toxicity and are not really known to bite. Immature females do not yet have the powerful poison stores that adults develop. The bodies of both genders are shiny and hairless. Juveniles start out brown, white and orange, growing more black as they age. Adult females are glossy and completely black with the trademark red 'hourglass' on the bottom of their round abdomen. Though males change in color and pattern as they mature, they are always smaller in size (by half) compared to the female. Females are known to eat the male after mating, earning them the name 'widow'. Females can store the sperm from one mating session and use it to produce subsequent batches of fertilized eggs. Lifespans for females range from one to three years; males may live about two months.

Found frequently in the southern U.S. states, this species is also called the Southern Black Widow. It tends to spin its web in places that may be disturbed or visited by humans, thus increasing the likelihood of an unfortunate encounter between the them. Webs are irregular in shape, but strong, and are built under stones, near openings of rodent holes, and in outbuildings such as sheds, outhouses or barns. The spider is unlikely to leave its web to hide from insect prey. It does not go out of its way to bite humans, but a female guarding her eggs is more inclined to attack and bite a threat rather than escape.

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 a headache.

If you suspect you have been bitten by a Black Widow, do not attempt to suck out the venom. Immediately wash the bite area with soap and water. Put ice on the bite site and elevate that body part. Seek medical attention immediately if symptoms persist or worsen. Though it is rare for humans to die from a Black Widow bite, early treatment can reduce pain and other symptoms, and hasten recovery. This treatment may include taking antivenom and other medications. Small children are particularly sensitive to the venom. Those with heart conditions may need hospitalization. Every human body is different. It is critical to let a medical professional assess the victim and treat this kind of spider bite.
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Taxonomic Hierarchy
Kingdom: Animalia
  Phylum: Arthropoda
    Class: Arachnida
      Order: Araneae
        Family: Theridiidae
          Genus: Latrodectus
            Species: mactans
Identifying Information
Scientific Name: Latrodectus mactans
Other Name(s): Southern Black Widow
Category: Spider
Size (Adult; Length): 3mm to 10mm (0.12in to 0.39in)
Colorwheel Graphic Colors: white, red, black, orange, brown, yellow, white
Descriptors: shiny, pattern, hourglass, widow, biting, venomous, harmful
Territorial Map
Prince Edward Is.  
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Territorial Reach (A-to-Z)
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Rhode Island
South Carolina
South Dakota
West Virginia
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British Columbia
New Brunswick
Newfoundland and Labrador
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Prince Edward Island
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Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.

Spider Anatomy
Graphic showing basic parts of spider anatomy
Legs: Spiders have four pairs of legs and these are attached to the cephalothorax.
Pedipalps: Small appendages near the mouth used as taste and smell organs.
Cephalothorax: Contains eyes, head, mouthparts, and legs.
Abdomen: Contains various organs related to digestion, reproduction, and web-making.
Spinnerets: Used in the production of spider silk for fashioning webs or catching prey.
NOTE: Unlike insects, spiders have both an endoskeleton (internal) and exoskeleton (external).