Are Marbled Orb Weavers Poisonous? Your Guide to this Intriguing Spider

Marbled orb weavers are colorful spiders known for their distinctive, large abdomens.

These spiders display a wide range of colors, including white, yellow, orange, tan, grayish, and even purple.

Their patterns vary, but they commonly have mottling and spotting of black, brown, or purple on their abdomens.

As interesting as they are to look at, many people wonder if marbled orb weavers are poisonous.

While their bites can be slightly painful, they are not considered dangerous to humans.

Their venom is not potent enough to cause severe reactions, making encounters with these spiders fairly low risk.

Are Marbled Orb Weavers Poisonous?

While marbled orb weavers are venomous in the sense that they use venom to subdue their prey, they are not considered dangerous to humans².

Their venom is not potent enough to cause significant harm or severe reactions in people.

In fact, bites from these spiders are quite rare and mostly occur when the spider feels threatened or accidentally comes into contact with a human.

In comparison to other venomous spiders such as the black widow or brown recluse, the marbled orb weaver has a relatively low risk of causing serious harm³.

The bite of a marbled orb weaver may cause some localized pain, itching, and mild swelling, but these symptoms usually subside within a short period of time.

There is also a low likelihood of an allergic reaction to the venom.

To help illustrate the differences in venom, here is a comparison table:

Spider	Danger to Humans	Venom Potency
Marbled Orb Weaver	Low	Mild
Black Widow	High	Potent
Brown Recluse	High	Potent

Classification and Taxonomy

The Marbled Orb Weaver belongs to the family Araneidae and the genus Araneus within the class Arachnida. This makes them part of the larger orb weaver spider group.

Here is a brief overview of the spider’s classification:

• Class: Arachnida
• Family: Araneidae
• Genus: Araneus
• Scientific name: Araneus marmoreus Clerck

Comparing Marbled Orb Weavers with other orb weavers, a key standout is their distinct appearance.

For instance:

Feature	Marbled Orb Weaver	Other Orb Weavers
Abdomen shape	Large and marbled	Smaller, diverse shapes
Colorations	Orange, yellow, white, grayish	Typically brown or beige
Pattern	Marbled, variable patterns	Simple, less detailed patterns

Physical Description and Identification

The marbled orb weaver spider has a distinct appearance.

Females usually measure 9 to 20 millimeters in length with a large abdomen that varies in color, commonly found to be orange with brown or purple markings and yellow spots.

On occasion, abdomens may be nearly white. The cephalothorax (head) is typically yellow or burnt-orange, displaying a central dark line and additional lines on either side ¹.

This species can be recognized by its:

• Large, colorful abdomens
• Dark markings on yellow or burnt-orange cephalothoraxes
• Presence of a central dark line and additional lines on either side of the cephalothorax

Habitat and Distribution

North America

Marbled orb weavers are widely distributed across North America, including regions like Canada, Texas, and North Dakota.

They inhabit wooded areas, particularly near edges of forests or alongside streams. Some common locations to find these spiders include:

• Alaska
• Oregon
• South Carolina
• North America’s Atlantic coast

Europe

Marbled orbweavers can also be found in Europe, although their distribution varies across the continent. In general, these spiders prefer wooded habitats in both warmer and cooler climates.

Asia

In Asia, marbled orbweavers have been spotted in countries like Japan.

Similar to their North American and European counterparts, they reside in varied forest environments and often establish their webs close to water sources.

Table showing the distribution of marbled orb weavers

Continent	Distribution	Habitat
North America	Canada, Texas, North Dakota, etc.	Wooded areas, forest edges, streams
Europe	Varies across the continent	Wooded habitats, warm and cool climates
Asia	Japan, and likely other countries	Forests, near water sources

Web and Hunting Behavior

Marbled orb weavers create intricate webs made of silk. Their webs are a type of orb web, which has a circular pattern.

The main features of these webs are:

• Circular pattern: Orb-shaped designs composed of radial and sticky spiral lines
• Signal thread: A non-sticky thread that helps detect prey by vibrating when disturbed

Moreover, orb webs offer a couple of advantages, such as:

• Efficient in capturing flying insects
• Provide a large surface area for prey to get trapped

However, there can be some drawbacks:

• Requires continuous rebuilding as they can get easily damaged
• Can be time-consuming to construct for the spider

Capturing Preys

Marbled orb weavers are skilled hunters, primarily feeding on flying insects. Their capture strategy involves two key elements:

1. Web construction: They build their orb webs at locations with high insect traffic, increasing the probability of capturing prey
2. Prey sensing: When an insect gets trapped in the web, the spider detects the movement through the signal thread and rushes to subdue its prey

Therefore, marbled orb weavers are proficient predators, relying on their orb-shaped webs and keen senses to trap and capture their meals.

Reproduction and Lifespan

Courtship

Male and female marbled orb weavers engage in a fascinating courtship process. The male typically vibrates his legs to attract the female’s attention, and if she is receptive, they mate.

Laying Eggs

Once mating is successful, the female lays her eggs – which can number in the hundreds.

She then creates an egg sac to protect them during development, often placing it in a hidden or guarded area.

Spiderling Development

The development of spiderlings within the egg sac is as follows:

• Eggs hatch within the sac
• Spiderlings grow and molt several times
• Once fully developed, they emerge from the sac

Therefore, male and female spiders each have distinct roles, and their lifespans differ as well.

Ecological Significance and Relationships

Marbled orb weaver spiders play a crucial role in their ecosystem as prolific predators. They prey on a variety of insects, such as:

• Flies
• Mosquitoes
• Moths

Their presence helps control insect populations in their habitats.

Conversely, orb weaver spiders can fall prey to predators like birds and certain wasps. For example, the parasitic wasp larvae can consume the spider’s abdomen as a source of nutrition.

Parasites and Commensals

Marbled orb weavers also share their ecosystem with organisms that have different relationships with them.

One example is the spiders from the family Theridiidae, which are known as tangle-web or cobweb spiders.

These spiders may live in close proximity to marbled orb weavers without any direct harm.

In contrast, certain parasites can have negative effects on orb weaver spiders.

Some cases even involve parasitic wasp species as mentioned before, laying eggs on the spiders themselves.

Marbled orb weavers and the closely related Argiope garden spiders can both be found in similar habitats.

They both contribute to the ecosystem by limiting insect populations as predators.

Comparison of Marbled Orb Weavers and Argiope Garden Spiders

Feature	Marbled Orb Weaver	Argiope Garden Spider
Size	9 to 20 millimeters (adult females)	14 to 25 millimeters (adult females)
Web	Orb-shaped webs	Orb-shaped webs with a zigzag pattern known as “stabilimentum”
Habitat	Forest edges, meadows, and gardens	Forest edges, meadows, and gardens
Coloration	Orange, brown, yellow, or white with varying markings	Black and yellow markings on the abdomen

Therefore, marbled orb weavers participate in complex ecological relationships as predators, prey, hosts, and neighbors to various species.

While they are not poisonous to humans, their presence contributes to the balance of their ecosystem.

Conclusion

The marbled orb weaver, with its captivating appearance and unique web-building skills, stands out as an intriguing inhabitant of wooded landscapes across North America, Europe, and Asia.

While marbled orb weavers are venomous, their venom poses minimal risk to humans, causing only mild, temporary symptoms.

These spiders play a vital role as skilled predators, helping control insect populations and participating in intricate ecological interactions.

Their presence enriches the delicate balance of their habitats, reflecting the interconnected nature of all species in the natural world.

Footnotes

1. Missouri Department of Conservation ↩ ↩²

2. Penn State Extension ↩ ↩²

3. U.S. Fish & Wildlife Service ↩

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about Marbled Orb Weavers. Scroll down to have a look at some of them.

Letter 1 – Bug of the Month December 2013: Pumpkin Spider

Subject: What is this??
Location: Gainesville, Georgia North
November 27, 2013 9:48 am
We live in North Georgia and I found this in our yard, completely terrifying.
What is this?
Signature: Emily

Dear Emily,
Don’t be terrified.  The Pumpkin Spider, Araneus marmoreus, is not dangerous to humans, though we cannot guarantee the risk of not getting a bite at 0%.  

We imagine that, if provoked, a large female Pumpkin Spider might bite, and though she does have venom, that venom is not considered harmful to humans, but it might result in localized swelling and tenderness. 

Because of its timely submission, and because of the quality of your photograph, we are tagging your Pumpkin Spider as the Bug of the Month for December 2013.
We are curious exactly what being from Georgia North means.

Letter 2 – Bug of the Month November 2018: Pumpkin Spider

Subject:  The great pumpkin
Geographic location of the bug:  central NJ
Date: 10/31/2018
Time: 09:40 PM EDT
Your letter to the bugman:  I don’t have a clue, but it’s about as big as the orb-spinning house spider, and orange for halloween! Descended on silk from a tree. Is that an egg sac, or an abdomen?
How you want your letter signed:  LH

Dear LH,
We don’t know if you are serious about your subject line, but this does appear to be a Pumpkin Spider, which is how the orange color variation of the Marbled Orbweaver, Araneus marmoreus, is often called.

  Though the Pumpkin Spider was already our Bug of the Month for December 2013, we feel that enough time has passed to honor it again, so your submission will be featured as our Bug of the Month for November 2018. 

Like other Orbweavers, though there is a possibility that a large individual might inflict a bite, the Marbled Orbweaver is considered harmless.  The large abdomen of this female indicates she might still have to produce an egg sac or two before winter.

Thanks so much!
I’m interested in what type of webs it spins- the usual big bullseye?
This one was inside for a few days!

Letter 3 – Marbled Orb Weaver

What is this bug
A friend sent this to me and ask what it was. Have any ideas? Thanks
Wayne

Hi Wayne,
This is a Marbled Araneus Orb Weaver Spider, Araneus marmoreus.

Letter 4 – Marbled Orb Weaver

what’s this spider?
Hi:
Found this guy hanging out on our siding. Never seen one like this in our area. We live in Upper Michigan .
Thanks
Mark

Hi Mark,
It appears you have a photo of a Marbled Orb Weaver, Araneus marmoreus. These are shy spiders that hide in a retreat, only emerging when prey has been snagged in their web. It is found throughout the United States, north to Alaska.

Letter 5 – Marbled Orb Weaver

a picture for you
Please identify this spider for me or tell me if the image didn’t come through. The spider is a vivid orange with black markings.
Carol

Hi Carol,
This is a beautiful Marbled Orb Weaver, Araneus marmoreus. The spider hides in a retreat from its web and drops to the ground when approached and disturbed.

Letter 6 – Marbled Orb Weaver

Please ID this spider!
Thu, Nov 6, 2008 at 3:19 PM
We found this spider in our garage in Cincinnati, OH about a week ago. (late Oct. early Nov.). I dont think it had rained or anything but it is not a spider that I have ever seen in the area before. Its body w/o the legs is a little smaller than 1/2 inch. If you need any other info or pics just email me. Thanks for any help!
Mikey
Cincinnati, OH

Hi Mikey,
What a positively gorgeous Marbled Orb Weaver, Araneus marmoreus, a highly variable species whose many variations can be viewed on BugGuide.