Uuniversit of Florida Extension ServiceUF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail: indianco@ufl.edu 

August 15, 2007

Quick Links:    Banana Spider    Crab Spider      Writing Spider    References

Feature Article - for release the week of  August 19, 2007

Garden orbweaver web

Orb-weaving spiders produce round webs of various sizes. This Garden Orbweaver web measures about 3 feet in diameter. Photo: Dan Culbert, UF/IFAS 

 Bananas, Crabs and other Garden spiders

Over the past few weeks I have taken several calls asking about those large, ferocious-looking spiders that are appearing in our Florida Yards.  While little Miss Muffet may get scared away by some of these featured creatures,  local residents can thank them for helping to keep other lawn and garden pests from taking over our landscapes.

Spiders are not insects, but belong to a different group of organisms (Arachnids) with four pairs of legs, no antennae and two body regions. The spiders in today’s article are the Orbweaver spiders.  They are a large group of arachnids that spin “orbs” of wheel-shaped webs.  In Florida, there are many kinds of these spiders, some that are very common, while others are unusual.

None of these common spiders are particularly dangerous to people.  Spiders use venom to capture and digest insects which are their food.  Most spider bites result in nothing more than a sore, itchy swelling that goes away in a few days.  The spider will bite only if held or pinched, and the bite itself will produce only localized pain with a slight redness.

Of course, it is always a good idea to not handle the spiders to avoid bites.  If one of these Orbweavers builds a web near your home or garden, leave them alone. They aren't especially aggressive and don't like to leave their webs.  Instead, just watch and learn how fascinating these spiders can be.

 

 A Golden Giant

 "Banana"spider Notice the tufts of hairs on the legs of the "Banana spider"  Photo: Dan Culbert, UF/IFAS

Golden Silk Orbweaver A female Golden silk Orbweaver spider (Nephila clavipes). Photo:  UF/IFAS Golden Silk orbweaver Egg sac This is an egg sac with newly hatched spiderlings.  Note the Golden yellow color of the webbing.  Photo: Emily Earp or Josh Hillman, Florida Nature.org.

The Golden silk Orbweaver spider (Nephila clavipes) is well known to most native southerners.  It is sometimes called the “Banana spider” because of its large size and color.  The main part of the body is orange or greenish gold to brown, with small whitish spots.  Another key feature is the dark feathery tufts on its eight legs.

This is one of the largest orb-weaving spiders in the US.   The body of the female is 1 to 1 ½ inches long, plus an inch or two more when the legs are included in the measurements. The bodies of the males are much smaller, about ¼ inch, and are dark-brown.  They are often found in the webs of females.

Hikers and hunters hate this critter because large webs in late summer and fall make for a sticky trap.  The color of the web material is actually golden-yellow.  These webs may be three feet or more in size.  Banana spiderwebs are made in open woods or forest edges and are attached to trees and low shrubs; also look for them in tree tops or between utility wires.  These spiders are not usually found in row crops, where their webs are disturbed, but they are common in citrus groves.

These spiders feed primarily on flying insects.  Their prey consists of medium-sized flying insects like flies, bees, wasps, and small moths and butterflies.

Crabs on a web

"Crab" spider   

 

 

 

 

Spinybacked Orbweaver (Gasteracantha cancriformis). Photo:  UF/IFAS

Crablike Spiny Orb Weaver - Gasteracantha cancriformis - female   This photo shows some color variation of the Crab Spider, and some of the "tufts" found on the webs.  Photo Copyright © 2002 Troy Bartlett

A second spider that is often seen in our area is the Spinybacked Orbweaver (Gasteracantha cancriformis).  It is one of the most colorful and easily recognized spiders in Florida.

Sometimes referred to as the star or jewelbox spider, the preferred local name is the "crab spider." This spider somewhat resembles a small crab, even though it is not related to those that are correctly called crab spiders. 

 Many other spinybacked spiders are found in the tropics, and others with spines may be occasionally seen nearby.  But this one is the one most likely to be seen in Florida.

The top of the abdomen is usually white with black spots, and it has large red spines on the edge.  Females are ¼ to ½ inch long and 3/8 to ½ inch wide.  Males are much smaller than females (about 1/8 inch long) and slightly longer than wide.  The male coloreds are similar except they are gray with white spots and they also lack the big spines of the females.

Spinybacked webs typically contain tufts of silk, which may help keep birds from flying into them.  It is also thought that spines may make them more difficult for a bird to swallow them. These spiders feed on whiteflies, flies, moths, and small beetles that are caught in their circular webs.  The catching area of spinybacked web may be one or two feet in diameter, and are often strung between tree limbs.

Crab spiders are more common in the fall in woodlands and citrus groves are where they are most often seen.   Small golden yellow egg sacs are produced in the winter. 

Blackboards in the Garden

   Argiope aurantia: Female

Female Yellow and Black Garden Orbweaver (Argiope aurantia) showing her white band or stabilmentum  Photo: Dan Culbert, UF/IFAS

 Argiope aurantia: Male 

The male mate to the Yellow Garden Orbweaver shown in the photo to the left.  Photo: Dan Culbert, UF/IFAS

There are four species of garden orbweavers, each with slight differences in size and color. The Yellow and Black Garden Orbweaver (Argiope aurantia) is probably the most common in our area, and has several other common names,  such as the Writing spider.   This name may be the inspiration for the well known children’s story, Charlotte’s Web, because it makes a thickened, zigzag band of silk that looks like it was drawn on the web.

This distinctive white band is called a stabilmentum, and has generated a lot of debate as to its purpose. Their large webs can often be seen along the edge of woodlands. All of these Argiope spiders tend to hang with their head downwards in the middle of a medium-sized web. 

 Immature Writing spiders may produce thicker web bands that are round in shape.  Mature females make a characteristic zig-zag blaze that is quite distinctive.  Other species of garden orbweavers may make crosses or spiral patterns in their webs. 

The female Yellow Garden Orbweaver can reach a body length of one inch.  Its characteristic silver-gray carapace and yellow-and-black markings make it easy to identify. Also look to see if the legs are banded but not hairy.   There are several color variations, including some with tan brown or gray.  The male’s body is only ¼ inch long, and it generally is darker with more brown and red coloring.   They hang out on the side of the female’s web at this time of year.

 

If you are not convinced of the beauty of these Florida Yard creatures, I can refer you to a few excellent reference books (below) and photos on our web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on orb-weaving spiders, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons. GO GATORS!

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean. Last update: 08/18/2011.  This page is maintained by Dan Culbert    

References 

BugGuide: Argiope aurantia - Black & Yellow Argiope.  http://bugguide.net/node/view/2025 

Castner, J.L.  Common Florida Spiders [SP-118].  Gainesville: UF/IFAS Florida Cooperative Extension Service, June 2005.  http://edis.ifas.ufl.edu/IN017

Carson, Julie.  Yellow Garden Spider.  Immokalee: UF Master Naturalist Program Species Archive, 2007.   http://www.masternaturalist.ifas.ufl.edu/speciesarchive/argiope.htm 

Edwards, G.B.  Spiny orb weaver spider [formerly FDACS DPI Circular 308, EENY-167]. Gainesville: UF/IFAS Featured Creatures website, December 2005. http://edis.ifas.ufl.edu/IN324

Marshall, Sam and Edwards, G. B.  Florida's Fabulous Spiders.  Tampa: World Publications, 2002.  ISBN: 0-911977-21 This is the BEST book available on Florida Spiders!

Weems, H.V, and Edwards,G.B.  Golden silk spider.  [Featured Creatures EENY-229 (originally FDACS/ DPI Entomology Circular 193)].   Gainesville: UF/IFAS Extension Service, October 2004. http://creatures.ifas.ufl.edu/misc/golden_silk_spider.htm 

Image:Little Miss Muffet 1 - WW Denslow - Project Gutenberg etext 18546.jpg

 Stamp out Spiders!