Black widow spiders, belonging to the genus Latrodectus, are found globally. While often recognized, understanding their characteristics, especially appearance, helps in accurate identification and clarifies common misconceptions.
Color Variations Across Black Widow Species
Not all black widow spiders are uniformly black; their coloration varies significantly by species, sex, and age. A notable difference occurs between sexes.
Mature female black widows are typically shiny black, often with a distinctive red or orange hourglass marking on the underside of their abdomen. In contrast, male black widows are considerably smaller and frequently appear lighter in color, often brown or gray. They may have subtle markings, red or orange spots on their abdomens, or white stripes on their legs.
The coloration of black widows also changes as they mature. Young spiders can display a range of colors, including orange, brown, white, or yellowish-white. Through successive molts, juveniles gradually acquire more black pigmentation, developing the darker coloration characteristic of adult females.
The iconic hourglass marking itself can vary in color (red, orange, or yellow) and shape, from a complete hourglass to two separate triangles or dots. Different species within the Latrodectus genus, like brown widows (Latrodectus geometricus) and red widows (Latrodectus bishopi), also show distinct patterns. Brown widows range from tan to dark brown or gray, often with an orange or yellowish hourglass. Red widows are reddish-orange with spots instead of a full hourglass.
Key Identifying Features Beyond Color
Since color can be misleading, other physical and behavioral traits provide more reliable means of identifying black widow spiders.
Female black widows possess a distinctive globular, shiny abdomen, which is typically quite large relative to their overall body size. Their bodies generally measure around 1/2 inch (13 mm) in length. Males are significantly smaller, often half the size of females or even less.
Black widow spiders construct irregular, messy, and strong three-dimensional webs, often referred to as cobwebs. These webs are typically found in dark, undisturbed locations, such as woodpiles, under stones, or in secluded corners of structures, usually near ground level. Their legs are slender and relatively long, with males having proportionally longer legs than females. A unique feature is the “comb foot,” a row of strong, curved bristles on their hind legs, which they use to wrap silk around captured prey. These spiders are also shy and nocturnal, often hanging upside down in their webs.
The Origin of the “Black Widow” Name
The common name “black widow” stems from two distinct characteristics associated with these spiders.
The “black” portion refers to the prominent, shiny black appearance of the mature female in well-known species like the southern black widow. This dark coloration, combined with the vibrant hourglass marking, makes them easily recognizable.
The “widow” part originates from the historical belief that the female consumes the male after mating, a behavior known as sexual cannibalism. While this occurs in some species and laboratory settings, it is less common in the wild than popular belief suggests. This act of post-mating consumption contributed to the spider’s reputation and common name.