Arachnids of North Carolina
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View Araneidae Members: NC Records

Gasteracantha cancriformis - Spinybacked orbweaver


Taxonomy
Order: ARANEAEInfraorder: AraneomorphaeFamily: Araneidae                                                                                 
Comments: cancriformis (L), 'crab shaped'
Species Comment: Crab Spider, Spiny Orbweaver Spider, Crab-like Orbweaver Spider, Crab-like Spiny Orbweaver Spider, Jewel Spider, Spiny-bellied Orbweaver, Jewel Box Spider, Smiley Face Spider, Crablike Spiny Orbweaver.
Identification
Online Description/Photos: BugGuide, Google Images, iNaturalist, Wikipedia, GBIFTechnical Description: Spiders of North America - Bradley; Spiders of the Carolinas – Gaddy; Bugguide
Comments: A very distinctive spider with many color forms. Abdomen crab like with six spines around edge. Abdomen color can be white, yellowish to orange with dark spots, spines are tipped in black or red. Cephalathorax and legs are dark or black in color. The spinnerets are located on a raised tubercle under the abdomen, instead of the more normal position at the end of the abdomen. There is also a small projection from the underside of the abdomen that the male grasps while mating. Males are tiny are rarely seen. Males are much smaller than females, 2 to 3 mm long, and slightly longer than wide. Color is similar to the female, except the abdomen is gray with white spots. The large abdominal spines are lacking, although there are four or five posterior small hump
Total Length: Small, female total body length 5.8-8.6 mm, male total body length 1.9-2.7 mm.Adult ID: identifiable by photo
Structural Features: The six spines do not sting, and are used as a deterrent to avian predators only. These spiders can be handled by the abdomen without injury, but can deliver a mild bite to humans.
Distribution in North Carolina
Comments: Common throughout the coastal plain and piedmont. Found throughout the United States, emerging in spring, maturing in summer and surviving until the first frost, all year long during mild winters.
County Map: Clicking on a county returns the records for the species in that county.
Adult phenology:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Habitats and Life History
Habitats: Woodland edges, shrubby vegetation, gardens, agricultural areas including orchards and citrus groves.
Observation Methods: Visual observation, sweep netting and beat sheets.
Abundance/Frequency: Common
Silk / Web: Large orb webs, up to 50 cm (about 20 inches), are built in shrubs and the low branches of trees as well as on structures. Web is built at an angle to perpendicular. Web has white bands of thick silk alternating on the major lines of the web. Forms web in the morning and sits head down in center of web throughout the day. This spider adds little tufts of silk to its web that likely attract prey. According to Florida's Fabulous Spiders(2) "these little flags serve a warning function to prevent birds from flying into the web, destroying it." When a small insect flies into the web, she moves toward it, then snaps the radii on either side of the insect. In order to secure the prey, the spider snaps more of the web around the area, then rushes toward the prey in order to determine its exact location and bite it before carrying it back to the central disk where she feeds.
Prey: drosophilids, other small fly species, whiteflies, beetles, moths, etc.
Predators: The spider eggs are often attacked by parasitoid wasps and flies. (Levi, 1978; Muma and Stone, 1971)
Behavior: This species of spider does not live very long. In fact, the lifespan only lasts until reproduction, which usually takes place the spring following the winter when they hatched. Females die after producing an egg mass with 100-260 eggs, and males die six days after a complete cycle of sperm induction to the female. Egg sacs are usually attached to the underside of leaves, typically near the web. Egg sac is constructed with various colors of silk and includes a longitudinal dark green stripe. Males are sometimes found hanging from single silk lines near the webs of females. Laboratory studies of mating behavior show that males visit female webs, and use a 4-tap rhythmical-pattern drumming on the silk of the web. After several cautious approaches, males approach females, become strapped down with silk from the female, and copulate. Mating may take 35 minutes or more. After mating, the male remains on the female's web. Mating may occur repeatedly.
Status in North Carolina
Natural Heritage Program Status:
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Photo Gallery for Gasteracantha cancriformis - Spinybacked orbweaver

Recorded by: Erich Hofmann
Craven Co.
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Recorded by: Erich Hofmann and Kayla Weinfurther
New Hanover Co.
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Recorded by: B.Fleming
Carteret Co.
Comment: FOMA - Black and white color var. @ -76.681804, 34.695282
Recorded by: Marl Fox
Onslow Co.
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Recorded by: R. Newman
Carteret Co.
Comment: FOMA
Recorded by: Stephanie Haverstick
Harnett Co.
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Recorded by: Kim STONE
Franklin Co.
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Recorded by: Scott Bolick
Richmond Co.
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Recorded by: Brian Bockhahn
New Hanover Co.
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Recorded by: Jim
Cabarrus Co.
Comment: Residence back yard. Had been there 3 days. Bride says "begone". Moved to back of HOA.
Recorded by: Jim
Cabarrus Co.
Comment: Residence back yard. Had been there 3 days. Bride says "begone". Moved to back of HOA.
Recorded by: Brian Wagoner
Cumberland Co.
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Recorded by: Brian Wagoner
Cumberland Co.
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Recorded by: Susan O’Rourke
Wake Co.
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Recorded by: Susan O’Rourke
Wake Co.
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Recorded by: Susan O’Rourke
Wake Co.
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Recorded by: Susan O’Rourke
Wake Co.
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Recorded by: Mark Shields
Onslow Co.
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Recorded by: Julia A. Tennant
Wake Co.
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Recorded by: Julia A. Tennant
Wake Co.
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Recorded by: Shawn Tracy
Johnston Co.
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Recorded by: Brian Bockhahn
Durham Co.
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Recorded by: Paul Brotcke
Mecklenburg Co.
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Recorded by: Paul Brotcke
Mecklenburg Co.
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Recorded by: Brian Bockhahn
Harnett Co.
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Recorded by: Brian Bockhahn
Stokes Co.
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Recorded by: S. Crocker
Carteret Co.
Comment: FOMA - This specimen is showing the white dorsum coloration with some red on the spines. Some specimens have spines that can be red, black or a variation of the two.
Recorded by: R. Newman
Carteret Co.
Comment: FOMA
Recorded by: K. Bischof
Beaufort Co.
Comment: GOCR - Obs. Tar Kiln Trail.
Recorded by: J. Hawley
Beaufort Co.
Comment: GOCR
Recorded by: K. Bischof, J. Bischof, K. Bischof
Beaufort Co.
Comment: GOCR - Obs. along the Palmetto Boardwalk Trail adjacent to the Outdoor Classroom. @ -76.901604, 35.476599
Recorded by: F. Williams, S. Williams
Camden Co.
Comment: DISW - Egg case
Recorded by: J. Brown
Dare Co.
Comment: RUHI
Recorded by: Jane Wyche
Gates Co.
Comment: MEMI - with a very nice web in front of the old office building
Recorded by: FKW, SBW
Gates Co.
Comment: MEMI - Near outhouse at canoe-in group site.
Recorded by: F. Williams, S. Williams
Gates Co.
Comment: MEMI - Mid-winter in complete web
Recorded by: j.wyche, n.dominick
Gates Co.
Comment: MEMI - on Cypress Point Trail
Recorded by: j.wyche
Gates Co.
Comment: MEMI - old canoe area
Recorded by: j.wyche
Gates Co.
Comment: MEMI - north boundary
Recorded by: F. Williams, S. Williams
Gates Co.
Comment: MEMI
Recorded by: J. Wyche
Gates Co.
Comment: MEMI - 1 dropped from park visitor's gear onto the parking lot at the old canoe area; 1 in her web just S. of Millpond Bridge
Recorded by: j.wyche
Gates Co.
Comment: MEMI - boundary line b/t Millpond Rd. & Silver Springs Rd.
Recorded by: Jane Wyche
Gates Co.
Comment: MEMI - Cypress Point Trail
Recorded by: Jane Wyche
Gates Co.
Comment: MEMI - on Cypress Point Trail
Recorded by: C.Helms
Moore Co.
Comment: WEWO - Web head high streched about 10' between two longleaf pines.
Recorded by: NEW
Moore Co.
Comment: WEWO - egg case on oak leaf
Recorded by: Dorothy E. Pugh
New Hanover Co.
Comment: CABE - Near white sandy trail not far from the Cape Fear River.
Recorded by: A. Pharr
Wayne Co.
Comment: CLNE
Recorded by: Carol Tingley
Chatham Co.
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