Are Garden Orb Spiders Poisonous

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	ORB-WEAVER SPIDERS Critter Files/Spiders/Orb-Weaver Spiders By Blake Newton University of Kentucky Department of Entomology


Black & Yellow Argiope»	Marbled Spider»	Star-Bellied Spider»	Arrowshaped Micrathena»

Spined Micrathena»	White Micrathena»	Furrow Spider»	Acacesia hamata»

Cyclosa sp.»	Gea heptagon»	Arrowhead Spider»	Neoscona sp.»


Bolas Spider»

TAXONOMY

KINGDOM: Animalia | PHYLUM: Arthropoda | CLASS: Arachnida | ORDER: Araneae | FAMILY: Araneidae (orb-weaver spiders)

Other Names: Araneids

WHAT IS AN ORB_WEAVER?
LIFE CYCLE
ECOLOGY
PEST STATUS
COMMON KENTUCKY ORB WEAVERS
COLLECTING & PHOTOGRAPHY
ORB WEAVER FACTS
MYTHS, LEGENDS, AND FOLKLORE

WHAT IS AN ORB WEAVER?

Orb Weavers are difficult to distinguish from other kinds of spiders that live in webs, especially cobweb spiders.

The best way to tell the difference between orb weavers and cobweb spiders is by looking at the web itself: the webs made by orb-weavers are very organized, and resemble a circular grid. The webs of cobweb spiders appear disorganized and messy. Orb weavers have 8 eyes, and they usually have large spherical abdomens. Like all spiders, orb weavers have 8 legs, 2 body parts, and fang-like mouthparts called "chelicerae."	Typical Orb Web


SIZE: Body length up to about 1/2"

LIFE CYCLE

Simple metamorphosis: like all spiders, young orb-weaver spiders hatch from eggs and look like tiny adults. They shed their skin as they grow. Many Kentucky orb weavers only live for one year or less. At the end of the summer, many female orb weaver species produce a large amount of eggs (sometimes hundreds) that they wrap in a silken egg case. The young spiders hatch in the spring.

ECOLOGY

Orb weavers are very common in Kentucky, and can be found almost anywhere. They need weeds, fences, trees, walls, or other upright structures to build their webs. Orb weavers will eat almost anything small enough to get trapped in their webs, especially small insects and other spiders. Like many web-building spiders, orb weavers tend to have poor vision: they don't need to see very well to hunt because they can "feel" whenever prey gets caught in their webs.


PEST STATUS

Orb-weaver spiders are considered beneficial to humans. They eat flies, mosquitoes, ants, and other pest insects. Although many can give a painful bite, no Kentucky orb-weaver spiders are considered dangerous to humans (except to rare individuals who have severe allergic reactions to insect and spider bites).


COMMON KENTUCKY ORB WEAVERS


We have many species of orb weavers in Kentucky. Although most of them are similar in shape, orb-weaver spiders come in a wide variety of colors and patterns. Shown below are some of the most common and distinctive orb-weavers.


BLACK AND YELLOW ARGIOPE GENUS and SPECIES: Argiope aurantia One of Kentucky's largest spiders is an orb weaver called the Black and Yellow Argiope, Argiope aurantia, pictured below. Commonly called "garden spiders," these orb weavers can be almost 3 inches long from leg tip to leg tip. Argiope spiders are very common in backyard gardens, and have given a fright to many a homeowner. Although they are large and intimidating, their bite is only dangerous to people who experience severe allergic reactions to insect and spider bites. The picture below was sent to us by Mindy Crosby from Louisville, KY. Argiope spiders are also called "writing spiders" because of the bold zigzag pattern that they build into their web. This webpage from the University of Michigan has lots of detailed info about Argiope spiders.

Black & Yellow Argiope, Argiope aurantia (M. Crosby, 2006)



MARBLED SPIDER GENUS and SPECIES: Araneus marmoreus Pictured below is the Marbled Spider, Araneus marmoreus. This large, colorful spider is common in urban areas, and is over 1/2" long.

The Marbled Spider, Araneus marmoreus (R. Bessin, 2000)



STAR-BELLIED SPIDER GENUS and SPECIES: Acanthepeira stellata Shown below is a common orb-weaver called the Star-Bellied Spider, Acanthepeira stellata (1/2"). It was photographed in a meadow at the Buckley Wildlife Sanctuary in Franklin County, Kentucky.

Star-Bellied Spider (B. Newton, 2003)



Micrathena spp. GENUS: Micrathena Orb-weaver spiders in the Micrathena genus are known for their distinctive spikes and vibrant colors. T he Arrowshaped Micrathena and the Spined Micrathena are about 1/2" long and are common in meadows, along the edges of forests, and along woodland trails in Kentucky. The White Micrathena is smaller, at about 1/4". It is also common on trails and in meadows. All of these spiders are notorious for weaving their webs at face-level along trails.

Arrowshaped Micrathena, Micrathena sagittata (R. Bessin, 2003)	Spined Micrathena, Micrathena gracilis (R. Bessin, 2003)

White Micrathena, Micrathena mitrata (B. Newton, 2005)



FURROW SPIDERS GENUS: Larinoides Furrow Spiders are common orb-weaver spiders often found around homes and other urban areas. Some furrow spiders are known to overwinter as adults: this is noteworthy because typical orb weaver species live for only one season, dying before winter. Several species of furrow spiders live in Kentucky and they all look very similar. Furrow spiders formerly belonged to the genus Nuctenea , but now belong to the genus Larinoides. These species grow to about 1/2" long.

A Furrow Spider (B. Newton, 2003)



*Acacesia hamata* GENUS and SPECIES: Acacesia hamata Pictured below is a colorful orb-weaver, Acacesia hamata (1/8"). It was photographed on Queen Anne's Lace at the Raven Run Nature Sanctuary in Fayette County.

Acacesia hamata (B. Newton, 2003)



*Cyclosa spp.* GENUS: Cyclosa Orb weavers in the *Cyclosa* genus have a unique cone-shaped abdomen. These spiders (sometimes called "Trashline Orbweavers") maintain a line of debris in their webs (consisting of dead prey and shed-skin) and camouflage themselves among the debris when threatened. The one pictured below was about 1/4" long and was photographed in the Floracliff Nature Sanctuary in Fayette Co., Kentucky.

Cyclosa sp. (B. Newton, 2005)



*Gea heptagon* GENUS and SPECIES: *Gea heptagon* Gea heptagon is about 1/4" long with a bold color pattern and distinctive spines on the abdomen. A female is pictured below. Males have a similar shape, but are patterned with red and orange. A male Gea heptagon is pictured at Bugguide.net.

Gea heptagon female (B. Newton, 2004)



Arrowhead Spider GENUS: Verrucosa arenata The Arrowhead Spider, Verrucosa arenata, is common in Kentucky forests and meadows. It is a little less than 1/2" long and has a distinct white or yellow triangular pattern on the abdomen. Like orb-weavers in the Micrathena genus (pictured above), Arrowhead Spiders are notorious for building webs across forest trails at face-level.

The Arrowhead Spider, Verrucosa arenata (B. Newton, 2005)



Neoscona spp. GENUS: Neoscona Orb-weavers in the Neoscona genus are usually large, about 1/2" long or longer. They are commonly seen around buildings in the late summer and fall in Kentucky and they are sometimes called "barn spiders" or "spotted orb weavers". The one below was photographed in Lexington, KY, by Fred Fahmy, who has kindly allowed us to use the image here. Also pictured is a view from the underside of a spider from this genus (photo by Jim Occi, used with permission from www.bugwood.com).

Neoscona sp. (F. Fahmy, 2006)

Neoscona sp., underside (J. Occi, 2004)



BOLAS SPIDERS GENUS: Mastophora, others Bolas Spiders , like the one pictured below, are also in the orb-weaver family. However, they do not build typical orb webs. Instead of waiting for an insect to get trapped in a web, bolas spiders use chemicals to attract their prey. When a victim get close enough, a bolas spider slings a sticky wad of webbing (just like a "bolas" used by human hunters) with its front legs and snags its prey right out of the air. Scientists at the University of Kentucky Department of Entomology have been studying bolas spiders for years. Read more about this research here.

Bolas spider, Mastophora sp. (R. Bessin, 2000)

COLLECTING & PHOTOGRAPHY

Orb weavers can be found almost anywhere, indoors and outdoors. Orb weavers and cobweb spiders tend to inhabit similar types of environments, although orb weavers may be more common in wild areas than they are around buildings and other places where people live. If you are careful, an orb-weaver will remain still in its web for a photograph as long as you don't disturb it. Like all spiders, orb-weavers should be preserved in alcohol.

ORB-WEAVER FACTS

True orb-weavers (Araneidae) and long-jawed orb-weavers (Tetragnathidae) are the only common kinds of Kentucky spiders that make orb webs. The webs of most other kinds of spiders, such as cobweb spiders, appear messy and disorganized.

MYTHS - LEGENDS - FOLKLORE

Casey Hauser from Winston-Salem, North Carolina, sent us this urban legend about writing spiders: "I was always told when I was younger to never say your name or the name of a loved one around these spiders because any name they heard they would write in their web and that person would die." We had never heard this one before, but it is very interesting (and creepy). Thanks, Casey!

Donna Welch from Abbeville, South Carolina, was told as a child that that a person will die if a writing spider "counts your teeth." This saying is also associated with millipedes. We hope it is not true for either organism!

Do you know any myths, legends, or folklore about orb-weaver spiders? If so, let us know.

Original document: 25 May 2004
Last updated: 12 Feb 2010

Photos courtesy R. Bessin and B. Newton, University of Kentucky, except where otherwise noted.
The Kentucky Critter Files are maintained by Blake Newton, Department of Entomology, University of Kentucky.
Contact: blaken@uky.edu