Arachnids of North Carolina
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View Theridiidae Members: NC Records

Latrodectus mactans - Southern black widow


Taxonomy
Order: ARANEAEInfraorder: AraneomorphaeFamily: Theridiidae                                                                                 
Identification
Online Description/Photos: Differentiation between L. mactans and variolus is often based on the mactan's loss of dorsal markings on the abdomen, and the contiguous nature of its infamous ventral "hour glass." Furthermore, mactans is more common species in NC common, and typically occurs in warmer regions of the state, including the coastal plain. None of these characteristics is definitive, however, and much variation occurs. The males can be separated by the number of lateral lines on the abdomen: L. mactans has three, while variolus has four. (Females are virtually impossible to determine short of dissecting the epigynum, where one finds conducting ducts having four coils, while variolus has but three.) BugGuide, Google Images, WikipediaTechnical Description: Kaston, B. J. (1970). Comparative biology of American black widow spiders. Transactions of the San Diego Society of Natural History 16: 33-82.
Comments: Females are shiny black, brown-black, with possibly a row of red spots on the top of the abdomen along the midline. Two reddish triangles resembling an hourglass are present on the underside of the abdomen. The male’s abdomen usually has red spots along the upper midline and white lines or bars radiating out to the sides. (The number of bars can indicate which species.) Hourglass primarily complete, posterior half (next to spinnerets) 'always' wider than anterior half when complete. Hourglass marking may be complete, split*, partial*, or absent. Adult male hourglass primarily complete. Southern black widows have a longer than wide second orange/red spot on the abdomen.
Distribution in North Carolina
Comments: Common in the southeast, but extends into S. NY & New England, W. through S. OH, IN, IL, MO, and central Kansas. S through OK and TX.
County Map: Clicking on a county returns the records for the species in that county.
Adult phenology:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Habitats and Life History
Habitats: roadside, pasture, woodpile, under rocks, in sheds, in loose bark ; tangle of tough silk, funnel retreat
Observation Methods:
Abundance/Frequency:
Silk / Web: As do other theridiid species, Latrodectus constructs a gumfoot web, which effectively ensnares substrate-bound prey.
Prey: Virtually anything that stumbles into the web, including non-insects, such as lizards, frogs, snakes, and mice.
Behavior: Females are sedentary, staying on or near their web. They will bite if molested. Males and immatures are harmless.
Status in North Carolina
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Photo Gallery for Latrodectus mactans - Southern black widow

Recorded by: Newman, Randy
Carteret Co.
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Recorded by: K. Bischof
Beaufort Co.
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Recorded by: K. Bischof
Beaufort Co.
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Recorded by: J. Davis, E. Taylor
New Hanover Co.
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Recorded by: D. Pell
Wake Co.
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Recorded by: R. Newman
Carteret Co.
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Recorded by: R. Newman
Carteret Co.
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Recorded by: Hunter Phillips
Onslow Co.
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Recorded by: J. Anderson
Ashe Co.
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Recorded by: K. Bischof
Transylvania Co.
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Recorded by: M. Gosselin
Dare Co.
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Recorded by: L. Appling
Watauga Co.
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Recorded by: K. Bischof
Beaufort Co.
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Recorded by: K. Bischof
Beaufort Co.
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Recorded by: K. Bischof
Chatham Co.
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Recorded by: K. Bischof
Chatham Co.
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Recorded by: K. Bischof
Chatham Co.
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Recorded by: J. Wyche
Gates Co.
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Recorded by: Newman, Randy
Carteret Co.
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Recorded by: Newman, Randy
Carteret Co.
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Recorded by: Newman, Randy
Carteret Co.
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Recorded by: Jane Wyche
Gates Co.
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Recorded by: JWP
Surry Co.
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Recorded by: Donald B. ZEPP
Johnston Co.
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Recorded by: Brian Bockhahn
Halifax Co.
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Recorded by: Brian Bockhahn
Stokes Co.
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Recorded by: Brian Bockhahn
Cumberland Co.
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Recorded by: Brian Bockhahn
Rockingham Co.
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Recorded by: Brian Bockhahn
Stokes Co.
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Recorded by: Mark Shields
Onslow Co.
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