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(female; this white form with red spines is most common in Florida)
Primary County Record Source: Allen Dean
Range: North Carolina, to Florida, to Texas, south to northern Argentina. Rare in southern California.
Bastrop, Bell, Bexar, Brazoria, Brazos, Burleson, Cameron, Gonzales, Grimes, Harris, Hidalgo, Leon, Nacogdoches,
Shelby, Travis, Van Zandt, Walker, Wharton, Wichita, Zapata (Allen Dean, Pers. Comm., 2007)
Coryell, Fort Bend, Galveston, Smith, Starr, Tarrant, Victoria, Williamson. (M.OB., 2007)
Activity Period: Nearly year round, but most common in fall.
For females, white is the most common color form, followed by yellow, orange and then red.
Red-spined form predominates in Florida and is common in Georgia and South Carolina as well.
Black-spined form predominates everywhere except the east coast.
Males are much smaller than females, 2 to 3 mm long, and slightly longer than wide. Abdomen is gray with white spots. Small bumps are in the place of the female's large abdominal spines.
Webs have extra tufts of silk, primarily on the foundation lines, that Eisner and Nowicki (1983) suggest serve to make the web more apparent to birds so they don't fly into and destroy it.
Similar species: Species is unique in North America.
spinybacked orbweaver - University of Florida
Gasteracantha cancriformis - The Nearctic Spider Database
Gasteracantha cancriformis - Animal Diversity Web, University of Michigan Zoology
Spiny-Backed Orb Weaver - Excellent series of life history photos by Larvalbug.com
Egg sac - University of Florida
Yellow and Orange forms - BugGuide.Net
Adult male - Jeff Hollenbeck
Web with extra tufts - BugGuide.Net
Multiple Photos - BugGuide.Net
Close-up photos of orange form
Spinybacked Spider - 33 cent USA
Insects & Spiders - VERY high resolution - full sheet - 1999 - Illustrator Steve Buchanan - USPS
Etymology: Gasteracantha cancriformis (Linnaeus, 1758)
gast, =er (G). The stomach, belly
acanth, =a, -o (G). A spine, thorn
canc, =er, -r, -ro (L). A crab
form, =a (L). Form, shape
Biography: Carl Linnaeus (1707-1778) - University of California, Berkeley
Comstock, J.H. 1940. The Spider Book. Comstock Publishing Co., Ithaca, New York.
Eisner T, & S. Nowicki. 1983. Spider web protection through visual advertisement: Role of the stabilimentum. Science 219: 185-187.
Gregory, B.M. Jr. 1989. Field observations of Gasteracantha cancriformis (Araneae, Araneidae) in a Florida mangrove stand. Journal of Arachnology, 17: 119-120.
Jackman, J.A. 1997. A Field Guide to the Spiders and Scorpions of Texas. Gulf Publishing Co., Houston. 201 pp. To order call: 800-462-6420.
Kaston, B.J. 1978. How to Know the Spiders, 3rd ed. Wm. C. Brown, Dubuque, Iowa.
Levi, H.W. 1978. The American orb-weaver genera Colphepeira, Micrathena and Gasteracantha north of Mexico (Araneae, Araneidae). Bulletin of the Museum of Comparative Zoology Harvard 148: 417-442.
Levi, H.W. 1996. The American orb weavers Hypognatha, Encyosaccus, Xylethrus, Gasteracantha, and Enacrosoma (Araneae, Araneidae). Bulletin of the Museum of Comparative Zoology Harvard, 155: 89-157.
Levi, H.W. and L.R. Levi. 1968. A Guide to Spiders and Their Kin. Golden Press, New York.
Linnaeus, C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus differentiis, synonymis, locis. Editio decima, reformata. Holmiae, 821 pp. (Araneae, pp. 619-624)
Muma, M.H. 1971. Biological and behavioral notes on Gasteracantha cancriformis (Arachnida: Araneidae). Florida Entomologist, 54(4): 345-351.
Muma, M.H., & K.J. Stone. 1971. Predation of Gasteracantha cancriformis (Arachnida: Araneidae) eggs in Florida citrus groves by Phalacrotophora epeirae (Insecta: Phoridae) and Arachnophaga ferruginea (Insecta: Eupelmidae). Florida Entomologist, 54(4): 305-310.
Schappert, P. 2007. Multicolored Orbweavers Are a Mystery. Lost Pines Nature Notes, No. 119.
27 Apr 2008 © Mike Quinn / email@example.com / Texas Entomology