Arachnids of North Carolina
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View Theridiidae Members: NC Records

Latrodectus mactans - Southern black widow

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

Recorded by: Erich Hofmann
Craven Co.
Comment: Two specimens found dead in yard, frozen until photographed		Recorded by: Erich Hofmann
Craven Co.
Comment: Two specimens found dead in yard, frozen until photographed
Recorded by: Erich Hofmann
Craven Co.
Comment: Two specimens found dead in yard, frozen until photographed		Recorded by: Ken Kneidel
Scotland Co.
Comment:
Recorded by: Jim Petranka and Becky Elkin
Madison Co.
Comment: They are commonly seen in our vegetable garden beneath rocks and other surface objects. A faint amount of red spotting is evident on the dorsum of the abdomen. 		Recorded by: Jim Petranka and Becky Elkin
Madison Co.
Comment: They are commonly seen in our vegetable garden beneath rocks and other surface objects. A faint amount of red spotting is evident on the dorsum of the abdomen.
Recorded by: Jim Petranka and Becky Elkin
Madison Co.
Comment: They are commonly seen in our vegetable garden beneath rocks and other surface objects. A faint amount of red spotting is evident on the dorsum of the abdomen. 		Recorded by: R. Newman
Carteret Co.
Comment: FOMA - Immature male @ -76.680848, 34.694934
Recorded by: Newman, Randy
Carteret Co.
Comment: FOMA - Fort restrooms		Recorded by: K. Bischof
Beaufort Co.
Comment: GOCR
Recorded by: K. Bischof
Beaufort Co.
Comment: GOCR - Male obs. on near the back entrance of the VC. @ -76.902065, 35.477621		Recorded by: J. Davis, E. Taylor
New Hanover Co.
Comment: CABE - Observed in traffic counter box on 8-16-02 at 2:30 p.m.
Recorded by: D. Pell
Wake Co.
Comment: WIUM - Female found in mail box at residence.		Recorded by: R. Newman
Carteret Co.
Comment: FOMA - Common in moat pump pit. @ -76.679595, 34.696407
Recorded by: R. Newman
Carteret Co.
Comment: FOMA - Common in moat pump pit. @ -76.679595, 34.696407		Recorded by: Hunter Phillips
Onslow Co.
Comment:
Recorded by: J. Anderson
Ashe Co.
Comment: NERI - visitor center		Recorded by: K. Bischof
Transylvania Co.
Comment: GORG - Obs. in Clyde Chappel Field. One was found in this area the day prior and was found again this day. A total of 4 were found in this area. One adult female, 2 juvenile females, and 1 young juvenile presumed to be a female also.
Recorded by: M. Gosselin
Dare Co.
Comment: JORI - In thicket behind ranger houses on soundside road		Recorded by: L. Appling
Watauga Co.
Comment: GRMO - At GRMO office
Recorded by: K. Bischof
Beaufort Co.
Comment: GOCR - Female obs. under a piece of driftwood on the Pamlico River Front near Ragged Point. Female with egg sac.		Recorded by: K. Bischof
Beaufort Co.
Comment: GOCR - Female obs. under a piece of driftwood on the Pamlico River Front near Ragged Point. Female with egg sac.
Recorded by: K. Bischof
Chatham Co.
Comment: JORD - Female found under log, near main entrance boat ramp. 		Recorded by: K. Bischof
Chatham Co.
Comment: JORD - Female found under log, near main entrance boat ramp.
Recorded by: K. Bischof
Chatham Co.
Comment: JORD - Female found under log, near main entrance boat ramp. 		Recorded by: J. Wyche
Gates Co.
Comment: MEMI - desiccated male on the visitor center
Recorded by: Newman, Randy
Carteret Co.
Comment: FOMA - Immature male on fort restroom building		Recorded by: Newman, Randy
Carteret Co.
Comment: FOMA - Fort restroom. Spider had Sesarma cinereum (Wharf Crab) in web. Crab was still alive.
Recorded by: Newman, Randy
Carteret Co.
Comment: FOMA - Fort restroom. Spider had Sesarma cinereum (Wharf Crab) in web. Crab was still alive.		Recorded by: Jane Wyche
Gates Co.
Comment: MEMI - in a storage room at the visitor center; It had a web wiith some left over food items in it. There was another spider caught in the web but not dead: That hunting spider appears to have gotten the better of the dead black widow.
Recorded by: JWP
Surry Co.
Comment: PIMO - Observed 3 males and 1 female at washhouse #2		Recorded by: Donald B. ZEPP
Johnston Co.
Comment: Behind a chunk of bark. Found likely prey source of many _Periplaneta americana_ adults and nymphs behind contiguous bark pieces.
Recorded by: Donald B. ZEPP
Johnston Co.
Comment: Behind a chunk of bark. Found likely prey source of many _Periplaneta americana_ adults and nymphs behind contiguous bark pieces.		Recorded by: Donald B. ZEPP
Johnston Co.
Comment: Behind a chunk of bark. Found likely prey source of many _Periplaneta americana_ adults and nymphs behind contiguous bark pieces.
Recorded by: Brian Bockhahn
Halifax Co.
Comment: 		Recorded by: Brian Bockhahn
Stokes Co.
Comment:
Recorded by: Brian Bockhahn
Cumberland Co.
Comment: 		Recorded by: Brian Bockhahn
Rockingham Co.
Comment:
Recorded by: Brian Bockhahn
Stokes Co.
Comment: 		Recorded by: Mark Shields
Onslow Co.
Comment: Adult female; found in a garage