NORTHERN BLACK WIDOW

Scientific name

Latrodectus variolus

Size

The average size of mature, female Northern Black Widow spiders is approximately .5 inch, with a leg span of 1.5 to 2 inches. Mature, male Northern Black Widow spiders are much smaller - approximately 1/3 the size of the female.

Description

Northern Black Widow spiders are a glossy jet-black, with a bright-red hourglass marking on the underside of their abdomen. The hourglass of the Northern Black Widow is typically incomplete, with the bottom half and top half separated. The bottom half (farthest from the head) is typically more rounded, rather than triangular. The Northern Black Widow will typically have a row of red dots running down the top of its abdomen, with white stripes running diagonally down the sides of the abdomen.

In addition to the typical hourglass marking on the underside of their abdomen, immature Black Widow spiders can vary greatly in the way they are marked on the top of their back. Typically they have red or white spots running down the middle of their back and white stripes running diagonally down the sides of the abdomen. In the Nothern Black Widow these markings are often retained as they mature.

Distribution

The Northern Black Widow is found throughout the eastern United States, sharing much of the same area as the Southern Black Widow, but found more often in the northern United States. Outside of the United States, the Northern Black Widow is found in Canada.

Notes

As with all widow spiders, only the female of the species is considered dangerous. The much smaller male is considered harmless. Northern Black Widow spiders are nocturnal, which means they are active during the nighttime. They spend most of their time hanging "upside down" in their web, which often makes the hourglass marking immediately visible.

Northern Black Widow spiders are typically not aggressive, and bite as a defensive measure when they are attacked or feel threatened. They will often retreat into hiding, but are more protective of their web when there are egg sacs present.

Web

The web of the Northern Black Widow does not resemble the typical spider's web, such as the garden spider's web, that is often associated with spiders. It instead resembles a cobweb, constructed of very strong white silk. The web will often be constructed under rocks or logs, or in large cracks and crevices, where it will be dark and the web will be protected from the weather. Webs will sometimes be constructed on lawn furniture, wood piles, sheds, barns, and in garages as well.

For more information on dangerously venomous spiders, please see the Venomous Links page.

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