Araneus gemmoides Chamberlin & Ivie, 1935

cat-faced spider

Males

Females

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How to Identify Araneus gemmoides Chamberlin & Ivie, 1935

Family: ARANEIDAE Simon, 1895

Genus: Araneus Clerck, 1757

Species: Araneus gemmoides Chamberlin & Ivie, 1935

Origin of Name: The Latin masculin word for spider is araneus.

Official Common Name: cat-faced spider

Other Common Names: jewel spider, cat spider, western plains orbweaver, plains orbweaver

Males

A = 3.97 mm
B = 3.38 mm
C = 2.93 mm

Females

A = 6.29 mm
B = 8.6 mm
C = 5.21 mm

Distinguishing Characteristics

The web is large and has about 20 radii (Levi, 1971). Male: Carapace is pale brown. Legs are yellowish brown with indistinct annulations (rings). Abdomen brownish, occasionally with indistinct paired oblique marks toward posterior end, and with distinct anterodorsal humps (Dondale et al., 2003). Female: Coloration as in male (Dondale et al., 2003).

Can Be Confused With

Where the two co-occur along the Pacific coast, inland to Southern British Columbia and Montana, Araneus gemmoides Chamberlin & Ivie, 1935 can be confused with Araneus gemma (McCook, 1888) (see below) but the latter has a paler dorsal, median line, often along the entire length of the abdomen.

Araneus gemma (McCook, 1888) female
(image coutesy Jason Sperfslage)

Range

USA, Canada: Southern British Columbia to southern Manitoba and Michigan, south to Baja California and Northern Florida.

Collection Map of Museum Specimens
in The Nearctic Spider Database

Typical Habitats

Individuals have been collected on barns and other outbuildings, under rock ledges, and lodgepole pine forests. They are also known to frequent well-lit human habitations under eaves, fencerows, and similar nooks.

Activity Patterns

Most commonly seen late summer to early autumn.

Importance

Although A. gemmoides Chamberlin & Ivie, 1935 is among the largest spiders in Western Canada and the United States, it is a docile creature. If severely provoked, it may on occasion bite but the effects of the venom are similar to that of a mild wasp sting with associated itchiness and mild swelling lasting no more than a few days.

Extra Reading

Buckle, D. J. 1999. The Plains Orb-weaver, Araneus gemmoides, in Saskatchewan. Blue Jay 57(4): 196-198.

Dondale, C. D., J. H. Redner, P. Paquin & H. W. Levi. 2003. The insects and arachnids of Canada. Part 23. The orb-weaving spiders of Canada and Alaska (Araneae: Uloboridae, Tetragnathidae, Araneidae, Theridiosomatidae). NRC Research Press, Ottawa, 371 pp.

Levi, H. W. 1971. The diadematus group of the orbweaver genus Araneus north of Mexico (Araneae: Araneidae). Bulletin of the Museum of Comparative Zoology, Harvard University 141(4): 131-179.

Other Web Pages

Royal Alberta Museum Bug Facts: Jewel Spider (Araneus gemmoides) (http://www.royalalbertamuseum.ca/natural/insects/bugsfaq/jewelspd.htm)

The Nearctic Spider Database (http://www.canadianarachnology.org/data/spiders/14895)

Recent Submissions

Observation Date: January 1, 2008 Coordinates: 46.7042, -112.0545 Observer: Sharon Liederman
Observation: I think this is a Araneus gemmoides. Can anyone confirm this? It came down from my ceiling on a string of silk. I'm puzzled as to why it would be out at this time of year and in my house. It's very beautiful.

Discuss (1)

Observation Date: October 6, 2007 Coordinates: 44.3214, -92.3112 Observer: Virginia A. Lindgren
Observation: Large female on her web in an interior doorway of a barn.
In the photo, she's perched on a 5-gallon bucket handle.

Discuss (0)