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, 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

99 photos are available. Only the most recent 30 are shown.

Recorded by: P. Murray on 2024-11-13
Rutherford Co.
Comment: 		Recorded by: P. Murray on 2024-11-13
Rutherford Co.
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Recorded by: Holly Webb on 2024-11-01
Pitt Co.
Comment: 		Recorded by: Holly Webb on 2024-11-01
Pitt Co.
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Recorded by: Brian Bockhahn on 2024-10-24
Pamlico Co.
Comment: 		Recorded by: Brian Bockhahn on 2024-10-23
Duplin Co.
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Recorded by: Brian Bockhahn on 2024-10-23
Johnston Co.
Comment: 		Recorded by: Kasie Lewis on 2024-09-25
Iredell Co.
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Recorded by: Kasie Lewis on 2024-09-25
Iredell Co.
Comment: 		Recorded by: Kasie Lewis on 2024-09-25
Iredell Co.
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Recorded by: Kane Alec Lawhorn on 2024-09-08
Hyde Co.
Comment: 		Recorded by: Mark Basinger on 2024-09-06
Wilson Co.
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Recorded by: Brenda Vaughan on 2024-08-19
Person Co.
Comment: 		Recorded by: Brenda Vaughan on 2024-08-19
Person Co.
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Recorded by: Christie J Poling on 2024-06-30
Nash Co.
Comment: 		Recorded by: Christie J Poling on 2024-06-30
Nash Co.
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Recorded by: G. Newman; R. Newman on 2024-05-19
Onslow Co.
Comment: 		Recorded by: Mark Basinger on 2024-03-30
Rowan Co.
Comment: Young, immature female
Recorded by: Mark Basinger on 2024-03-30
Rowan Co.
Comment: 		Recorded by: Mark Basinger on 2023-11-12
Wilson Co.
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Recorded by: Marissa Matthews on 2023-11-02
Cabarrus Co.
Comment: 		Recorded by: Mark BASINGER & Donald ZEPP on 2023-10-23
Greene Co.
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Recorded by: Terrell Tucker on 2023-10-14
Moore Co.
Comment: 		Recorded by: Yolanda Cristiani on 2023-10-03
Pamlico Co.
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Recorded by: Amanda J Wall on 2023-09-26
Gaston Co.
Comment: 		Recorded by: Amanda J Wall on 2023-09-26
Gaston Co.
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Recorded by: Amanda J Wall on 2023-09-26
Gaston Co.
Comment: 		Recorded by: Zachary Jones on 2023-09-26
Pitt Co.
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Recorded by: Brian Bockhahn on 2023-09-21
Dare Co.
Comment: 		Recorded by: Susan Schambach on 2023-09-17
New Hanover Co.
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