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Northern Black Widow (Latrodectus variolus)

The Northern Black Widow is a cool spider found mainly on the ‘East Coast’ of North America. It’s a close relative to the southern and western black widows. Female spiders from this group are really strong and make amazing 3D webs out in nature. Ready to discover more about them? Keep reading!

Table Of Content hide

Physical Description and Identification

Are Northern Black Widow Spiders Venomous?

Can Northern Black Widow Spiders Bite?

Ecological Importance and Behavior of Northern Black Widow Spider

Quick Facts

Did You Know

Physical Description and Identification

Adults

Size: Adult females are approximately 9-11 mm in length, and the males are 4-5 mm – that is, almost half the size of the former (both excluding legs).
Color: The characteristic hourglass mark in the Northern Black Widow is rather broken (unlike the female Southern Black Widow’s that has the hourglass mark distinct). Males have four diagonal whitish bands on each side of the abdomen.
Other Characteristic Features: Male black widows are not black, but are rather gray or brown with small red spots. Also, the males play their roles only for reproduction purposes and are mostly consumed by the females after mating or copulation.

Eggs

The females lay approximately up to 200 eggs that they incubate for around three weeks in a small, round, brown, papery sac that remains attached to the mother’s web.

Spiderlings

Like the males, the juveniles and immature specimens have two pairs of diagonal whitish bands on both sides of the abdomen. After hatching, the baby spiders remain in the cocoon for around four weeks. They are taken care of by the mother until they are mature enough to forage for themselves.

Are Northern Black Widow Spiders Venomous?

Yes, Northern Black Widow Spiders have venom. They use it mostly to catch the bugs they like to eat.

Can Northern Black Widow Spiders Bite?

While the venom of widow spiders is 15 times stronger than rattlesnakes’, they rarely bite as they are shy and prefer to run away when threatened. Even if bitten, the small amount of venom means it’s usually not deadly, with only a 1% mortality rate. Bites cause immediate pain, and redness, and can hurt for up to 24 hours.

Ecological Importance and Behavior of Northern Black Widow Spider

Northern Black Widows are important predators in their habitats. They control insect populations, which could otherwise become pests. Their impressive three-dimensional webs are not just for catching prey but also serve as protective structures for their offspring. They are shy by nature and exhibit remarkable maternal care.

Natural Predators: These spiders face predation from birds and larger spiders. This predation is a natural control on their populations, ensuring they do not become too numerous.

Prey-Predator Dynamics: The Northern Black Widow feeds primarily on insects but will also consume smaller spiders and arthropods. This diet makes them an integral part of the food web, controlling the insect population and providing food for their predators.

Relationship with Humans: While the Northern Black Widow’s venom is potent, they are timid and bites are rare. When they do occur, bites can be painful but are seldom fatal thanks to the small amount of venom injected. They prefer undisturbed natural habitats but can sometimes be found in human-inhabited areas, where their pest control benefits are welcomed.

Quick Facts

Other Names	Northern widow
Lifespan	1 to 3 years
Distribution	Ranges from northern Florida to south-eastern Canada
Habitat	Mostly prefer undisturbed woods, stumps, and stone walls
Common predators	Birds of prey, larger spiders
Diet	Mostly insectivorous, but might prey upon other smaller spider species and non-insect arthropods as well

Did You Know

These arachnids have been compared to widows mourning in ‘black’ cloaks for the unique appearance of the females, and the tendency to eat their mates.

In conclusion, the Northern Black Widow is a species that, despite its fearsome reputation, contributes significantly to the ecological balance through its predatory habits.

Frequently Asked Questions

What does a female Northern Black Widow look like?

A female Northern Black Widow is a glossy black spider, approximately 9-11 mm long, with a distinctive broken red hourglass marking on its abdomen. Unlike the connected hourglass of its southern relatives, this marking often appears as two separate reddish triangles. This feature is a key identifier for the species.

How can you tell a male Northern Black Widow from a female?

You can distinguish a male Northern Black Widow from a female by its smaller size and different coloring. Males are only 4-5 mm long and are typically gray or brown, not black. They also have four diagonal whitish bands on each side of their abdomen and may have small red spots.

Are Northern Black Widow spiders aggressive?

No, Northern Black Widow spiders are not considered aggressive and are naturally very shy. They will almost always choose to flee or hide when disturbed. Bites are a rare defensive measure, typically only occurring when the spider is accidentally trapped against a person’s skin and cannot escape.

How dangerous is a Northern Black Widow bite?

A Northern Black Widow bite is painful but rarely fatal for healthy adults, with a mortality rate of around 1%. The venom is potent and causes immediate pain and redness, but the small amount injected is usually not deadly. Always seek professional medical attention if you suspect you have been bitten.

How many eggs does a Northern Black Widow lay?

A female Northern Black Widow lays up to 200 eggs at once inside a small, brown, papery silk sac. She attaches this sac to her web and guards it for about three weeks during incubation. After hatching, the spiderlings remain inside the protective sac for approximately four more weeks.

What do juvenile Northern Black Widows look like?

Juvenile Northern Black Widows closely resemble adult males rather than the iconic black females. They are typically brown or gray and have two pairs of diagonal whitish bands running along the sides of their abdomen. They gradually darken and lose these markings as they mature into adults.

Where are Northern Black Widows commonly found?

Northern Black Widows are commonly found along the East Coast of North America, where they build strong, three-dimensional webs. They prefer sheltered, undisturbed locations close to the ground, such as in woodpiles, under stones, in hollow logs, and within outbuildings like sheds or barns where prey is available.

Northern Black Widow (Latrodectus variolus)