Barn Spider: All You Need to Know for a Worry-Free Farm Life

Barn spiders are fascinating creatures with distinct features and intriguing behaviors.

These spiders, also known as barn funnel weavers, inhabit various environments and often reside in man-made structures like barns and sheds.

Their impressive web-building abilities make them efficient hunters and essential components of their ecosystems.

Measuring between 7.5 to 11.5 millimeters for females and 6 to 9 millimeters for males, barn spiders display a unique appearance with a red-brown cephalothorax covered in pale-yellow hairs and two pale-gray longitudinal lines.

Their abdomen’s color can vary from pinkish to pale flesh, adorned with gray to black patches Barn Funnel Weaver Spider.

Some interesting facts about barn spiders include:

• Master web builders: they create funnel-shaped webs with a retreat at the end for capturing prey
• Nocturnal hunters: barn spiders are most active at night, consuming various flying insects
• Non-aggressive: though their bites may cause mild discomfort, barn spiders are generally non-threatening to humans

Overall, understanding the characteristics and habits of these intriguing arachnids offers valuable insights into their role within the environment, and how they coexist with humans.

Barn Spider Basics

Araneus Cavaticus

The barn spider, scientifically known as Araneus cavaticus, is a common orb-weaving spider found in North America.

Range and Habitat

These spiders are mainly distributed across the United States and Canada, particularly in the northeastern region. They enjoy dwelling in:

• Barns
• Sheds
• Porches
• Other man-made structures

Physical Appearance

A barn spider exhibits a unique appearance, characterized by:

• Grey, yellow, or brown coloration
• Black and white markings
• An overall orb-weaver body shape

Size and Sexual Dimorphism

Barn spiders exhibit sexual dimorphism, meaning the males and females differ in size:

• Females: 7.5 to 11.5 millimeters
• Males: 6 to 9 millimeters

Comparison of Barn Spider Size by Gender

Gender	Size (Length)
Female	7.5 to 11.5 mm
Male	6 to 9 mm

Behavior and Biology

Orb-weaving Webs

Barn spiders are known for their orb-weaving abilities.

They create spiral webs using their silk, which serve as a trap for insects. Some features of their webs include:

• Large, circular shape
• Spiral pattern
• Made of silk
• Sticky to catch prey

Diet and Predation

Barn spiders primarily feed on insects, which they catch in their webs. Examples of their prey include:

• Flies
• Mosquitoes
• Moths

Once caught, they quickly immobilize their prey by injecting venom and wrapping them in silk.

Poor Eyesight and Sensing Vibrations

Despite being predators, barn spiders have poor eyesight.

To compensate, they rely on sensing vibrations through their webs. This helps them:

• Detect trapped prey
• Identify potential threats
• Monitor the condition of their web

Nocturnal Activities

Barn spiders are mostly nocturnal, which means they are most active during the night. Below is a comparison of their day and night activities:

Activity	Daytime	Nighttime
Web building	Rarely	Most active
Hunting	Less active	Actively seeking
Web maintenance	Less focus	Greater attention

Overall, barn spiders exhibit interesting behaviors and biological adaptations that allow them to survive and thrive in their natural environments.

These fascinating creatures play a vital role in controlling insect populations, making their orb-weaving skills and nocturnal activities essential to both their wellbeing and the ecological balance.

Reproduction and Lifecycle

Mating

Barn Spiders are known for their fascinating mating rituals. Males approach females cautiously, tapping and vibrating the female’s web to signal their presence.

If the female accepts the male, they proceed with mating.

Egg Sacs

After successful mating, the female barn spider produces egg sacs, which are:

• Made of silk
• Round-shaped
• Creamy yellow to light brown in color

Each female can create multiple egg sacs, each containing up to a thousand eggs.

Spiderlings

Upon hatching, the spiderlings, which are tiny replicas of the adult spiders, emerge from the egg sacs. They:

• Go through several molting stages to grow
• Disperse by ballooning, where they travel through the air on a strand of silk

Lifespan

Barn Spiders have a relatively short lifespan. Here are some quick facts about their lifespans:

• Females: Usually live longer than males, around 12 months
• Males: Typically live up to 8 months
• After mating, females lay eggs and die soon after the egg sacs are produced

	Males	Females
Lifespan	Up to 8 months	Up to 12 months

Human Interaction

Venom and Bite

Barn Funnel Weaver spiders are not considered dangerous to humans.

Their venom is generally mild and not harmful to people. If bitten, a person may experience mild pain, temporary redness and swelling

These symptoms usually subside within a few hours.

Barn Spiders and Pest Control

Barn spiders can be beneficial in controlling pest populations. They feed on various insects, including:

• Flies
• Mosquitoes
• Beetles
• Moths
• Ants

This natural form of pest control can help reduce the need for chemical treatments.

Identifying and Control Measures

To identify Barn Funnel Weaver spiders, look for the following characteristics:

• Females: 7.5 to 11.5 millimeters in length
• Males: 6 to 9 millimeters in length
• Red-brown cephalothorax with pale-yellow hairs
• Pinkish to pale flesh-colored abdomen with gray to black patches

To control their population, consider these methods:

• Remove clutter and debris around your property
• Seal cracks and gaps in walls and foundations
• Use screens on windows and doors
• Regularly vacuum and clean indoor areas

Cultural Significance

Charlotte’s Web

Charlotte’s Web is a beloved children’s novel written by E.B. White. The story revolves around a compassionate barn spider named Charlotte A. Cavatica, who befriends a pig named Wilbur and devises a plan to save him from being slaughtered:

• Charlotte spells out words in her web to make people believe Wilbur is a special pig
• The text in the web becomes a sensation, attracting visitors to the farm
• This ultimately saves Wilbur’s life, as he becomes too valuable to be killed

Conclusion

Barn spiders, scientifically known as Araneus cavaticus, are notable orb-weaving spiders commonly found in North America, especially in barns, sheds, and other man-made structures.

These spiders exhibit a unique appearance, with females measuring between 7.5 to 11.5 millimeters and males between 6 to 9 millimeters.

Their webs are large, circular, and spiral-patterned, serving as efficient traps for insects like flies, mosquitoes, beetles, and moths. While they possess venom, it’s generally mild and poses minimal risk to humans.

These spiders play a vital role in controlling insect populations, contributing to ecological balance.

Their nocturnal activities, mating rituals, and unique web-building abilities highlight their fascinating biology and importance in the ecosystem.

Reader Emails

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

Letter 1 – Barn Spider

Huge Scary Spider, I’m shaking as I type this!
Hello,
I am from Austin, Texas and we have a very scary spider we’ve been keeping alive (sometimes even feeding it!) on our wooden porch Might I add that this area is wooded with no water close by.

His/Her web is a typical spider’s web you see in movies, not a funnel web or an orb web. It usually only comes out at night, burrowing between the metal and the glass during the day. It also usually sits with its legs drawn in.

Today I got a special treat, because it had just finished with its molting phase and its web was disturbed so its legs were extended and it out during the day to pose for my camera.

The pictures lighten its abdomen markings as they are more of a dark brown with visible hairs, and there are dark brown and white stripes on his legs.

In addition his butt is kind of raised up, in the shape of a tear drop. Might I add that I just went outside to check on it, and it jumped from the wall, falling to the ground.

I’ve never noted aggressive behaviour before like this, nor have I seen it jump before. I’m so scared now because its very fast, and when its legs are extended, its larger than a half dollar.
Please help!
Rissa
PS, I took a picture of the molted shell, and feel free to edit any of this!

Hi Rissa,
You have a Barn Spider, Araneus cavaticus. The spider builds a large orb web at night and stands in it, but generally seeks shelter above the web during the day. It is usually found in shady locations.

Letter 2 – Barn Spider: Common Orbweaver

Barn Spider?
Mon, Oct 6, 2008 at 7:47 PM
Hello,
I’ve seen this spider on the other side of my window every night now for about a month. It lives in the crevice of my window during the daytime and at night it comes down and sits in the middle of its web.

Its underside is black with two small white dots, and its a little bigger than a quarter. I’ve done my research and my best guess is that it’s a barn spider.

I don’t know if I can include links or not but I also have a video of it here: http://www.youtube.com/watch? v=qYO1y9cygQ0 (ignore the TV in the background)
Jnco
San Angelo, (West) Texas

Hi Jnco,
Your spider surely does look like a Barn Spider. Species in the genus Neoscona are commonly called Spotted Orbweavers and, according to BugGuide: “Some species (usually collectively referred to as “barn spiders”, i.e. Neoscona crucifera ) are nearly impossible to distinguish from Araneus and can only be separated by examination of carapace to view the carapace groove (fovea).

Neoscona have a longitudinal groove on the carapace (parallel with the long axis of the body), whereas Araneus have angular (transverse) grooves. However, an apparent problem is that in Araneus the groove may appear as little more than a dimple, making it tough to tell.

See this diagram for differences in the carapace grooves.” We have never taken identification quite that far, and due to individual variation within the species of Araneus and Neoscona, it is sometimes quite difficult for us to get more specific than to just identify a spider as an Orb Weaver.

We did find a nice chatty comment about the nocturnal habits of Neoscona hentzi or Barn Spider on an amusing website called Nature at Close Range. Also, according to BugGuide, Neoscona hentzi is synonymous with Neoscona crucifera.

It is embarrassing for us to admit it, but we haven’t ever bothered positively identifying our own species of Orbweaver. Our own nocturnal spinners get quite numerous in the autumn and they spin webs all over our garden and patio.

We had three large females spinning webs in close proximity to one another and our front porch light for weeks, but a few days ago, there were just two.

We have wondered about the fate of the third as her web remained in place from day to day, getting more and more tattered, while her sisters consumed their own webs each morning and resumed spinning anew when the sun sets each evening.

Since we have never gone to the extent of examining the anatomy of our own individuals, and are not certain of their exact genetic lineage, we can’t rule out entirely that they might have hybridized with other introduced species.

Geographical barriers that once separated individual populations from one another have been breached by man who is responsible for accidental introductions of many exotic specimens into new habitats.

Sometimes this has dire consequences, and sometimes these introductions may go unnoticed. We figure the spiders know best about mate selection, and species and subspecies are only categories created by humans in a feeble attempt to better understand the world around us.

Future taxonomists may even determine that Araneus and Neoscona need to be lumped together into one super-genus, but the bottom line is that the spiders know and we only presume to know.

We think Charles Hogue had the right idea in Insects of the Los Angeles Basin when he identified Neoscona oxacensis (probably a misspelled Neoscona oaxacensis or Western Spotted Orbweaver on BugGuide) as the Common Orb Weaver and wrote:

“This is our most common orb weaver; in late summer and fall, its moderate-sized webs adorn gardens everywhere in the basin.”

P.S. We are getting used to the nuances of our new website and we are pleased that we can include the date we received a letter in the body of the posting, and can allow our program to time stamp the actual posting date. Your letter marks the first time we are including this double date.

Letter 3 – Possibly Barn Spider

Subject: Daniel – Neoscona crucifera?
Location: Hawthorne, CA
October 26, 2013 8:49 am
Hi Daniel,
Can you confirm my tentative id of this happy spider?
Signature: Thanks, Anna Carreon

Hi Anna,
This might be a Barn Spider, Neoscona crucifera, but we are not certain.  Except for Orbweavers in the genus Argiope, and certain species in the genus Araneus, we do not feel confident enough to identify most Orbweavers to the species level. 

According to BugGuide:  “Can usually be distinguished from Neoscona domiciliorum by rusty red color and the lack of pattern on the abdomen” and “N. crucifera & N. domiciliorum build thier webs at dusk and then take the webs back down around dawn.” 

If the webs are removed during the day, it is a good indication that this is a Barn Spider.  It appears that your photos were taken during the day, which would indicate this is most likely not a Barn Spider. 

We will be postdating your submission to go live during a brief absence from the office in early November.

Hi Daniel,
The fact that this spider was on the web during the day confused me also, as I am aware that they normally do their thing at night. 

For some reason, there she was during the day and only on that day.  It is very strange.  She had two or three bees to work on, so maybe that is why she was still out in the open?
Anna