Arachnids of North Carolina
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View Theridiidae Members: NC Records

Latrodectus mactans - Southern black widow


Second red spot longer than wide
Hourglass complete
Taxonomy
Order: ARANEAEInfraorder: AraneomorphaeFamily: Theridiidae                                                                                 
Comments: The etymology of the genus name "Latrodectus" being in question, Cameron (2017) suggests it was created by Walckenaer to mean "biting secretly." The epithet "mactans", among other things means "slaughtering" or "killing."
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 the more common species in NC, 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 of the two species can be visually separated by the number of lateral lines on the abdomen: L. mactans has three, while variolus has four. (Females are virtually impossible to definitively determine short of dissecting the epigynum, where one finds mactan's conducting ducts having four coils, while variolus has but three.) BugGuide Google, iNaturalist, Wikipedia, GBIFTechnical 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
Natural Heritage Program Status:
Natural Heritage Program Ranks:
State Protection:
Comments:

 Photo Gallery for Latrodectus mactans - Southern black widow

52 photos are available. Only the most recent 30 are shown.

Recorded by: K. Williams on 2024-07-16
Surry Co.
Comment: 		Recorded by: J. Thomson on 2024-06-21
Macon Co.
Comment:
Recorded by: J. Thomson on 2024-06-21
Macon Co.
Comment: 		Recorded by: Brian Bockhahn on 2024-05-10
Chatham Co.
Comment:
Recorded by: Brian Bockhahn on 2024-05-10
Chatham Co.
Comment: 		Recorded by: Ashley Ratcliffe Shipp on 2024-04-14
Forsyth Co.
Comment:
Recorded by: Ashley Ratcliffe Shipp on 2024-04-14
Forsyth Co.
Comment: 		Recorded by: Ashley Ratcliffe Shipp on 2024-04-14
Forsyth Co.
Comment:
Recorded by: Andrew W. Jones on 2024-03-25
Polk Co.
Comment: 		Recorded by: Andrew W. Jones on 2024-03-25
Polk Co.
Comment:
Recorded by: J. Perry on 2023-08-19
Stokes Co.
Comment: 		Recorded by: Jim Petranka and Becky Elkin on 2022-06-07
Madison Co.
Comment:
Recorded by: Jim Petranka and Becky Elkin on 2022-06-07
Madison Co.
Comment: 		Recorded by: Jim Petranka and Becky Elkin on 2022-06-07
Madison Co.
Comment:
Recorded by: Mark Basinger on 2021-05-22
Rowan Co.
Comment: 		Recorded by: R. Newman on 2021-04-19
Carteret Co.
Comment:
Recorded by: R. Newman on 2020-11-22
Carteret Co.
Comment: 		Recorded by: R. Newman on 2020-11-22
Carteret Co.
Comment:
Recorded by: Ken Kneidel on 2020-09-24
Scotland Co.
Comment: 		Recorded by: Donald B. ZEPP on 2020-09-16
Johnston Co.
Comment: subadult captured 19 Oct 2020; died 30 May 2022. See following ex situ postmortem adult photos. White ring is reflection of camera's ring light.
Recorded by: Donald B. ZEPP on 2020-09-16
Johnston Co.
Comment: White ring is reflection of camera's ring light.		Recorded by: Donald B. ZEPP on 2020-09-16
Johnston Co.
Comment: subadult captured 19 Oct 2020; died 30 May 2022
Recorded by: Erich Hofmann on 2020-06-29
Craven Co.
Comment: 		Recorded by: Erich Hofmann on 2020-06-29
Craven Co.
Comment:
Recorded by: Erich Hofmann on 2020-06-29
Craven Co.
Comment: 		Recorded by: Hunter Phillips on 2019-07-09
Onslow Co.
Comment:
Recorded by: Brian Bockhahn on 2016-09-05
Cumberland Co.
Comment: 		Recorded by: Brian Bockhahn on 2015-09-26
Rockingham Co.
Comment:
Recorded by: Brian Bockhahn on 2015-05-19
Stokes Co.
Comment: 		Recorded by: M. Gosselin on 2014-07-06
Dare Co.
Comment: