Adult female. Upper Newport Bay, Newport Beach, CA. Beginning 5 Nov. 2005
Longitude W 117.8858718081394; Latitude N 33.65373347788835
Copyright: Peter J. Bryant (pjbryant@uci.edu). Originals available from Biological Photo Service.
Bolas spider
Mastophora cornigera
Araneae: Araneidae
During the day, the female Bolas spider is inactive, although she can often be found in fairly exposed places. The male is much smaller than the female. The females provide a remarkable example of aggressive mimicry when they release chemicals similar to the sex attractants that are produced by female moths to attract males. They produce three chemicals that are identical to those produced by the moth. Thus, the main prey for these spiders is male moths.
Stowe, Mark K., et al; "Chemical Mimicry: Bolas Spiders Emit Components of Moth Prey Species Sex Pheromones," Science, 236:964, 1987.
Bolas spiders were featured on David Attenborough's TV series "Life in the Undergrowth" (2006).
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Shortly after dusk, the spider lowers herself on silk threads, spins a silk line with a sticky blob on the end of it and swings it to catch the moths or other insects that have been attracted by the chemicals. The spider gets its name from the bolas (ball-on-a-string) weapon used by Eskimos and South American Indians
Here she has caught a cranefly
Here she is hauling it in.
Here she is sucking blood from her prey
Here she has caught a moth, wrapped it in silk, and is feeding on it.
The egg cases of this spider are round balls hanging on silk straps. When discovered, in November 2005 on a kiosk at the Peter and Mary Muth Interpretive Center at Upper Newport Bay, Newport Beach, California, this female had already made eight egg cases and hung them on a web. Two weeks later, another egg case had appeared!
24 May 2006: Adult male just emerged
Adult male on web. Spider provided by Lenny Vincent.
Adult female and four egg cases. Boat Road, Laguna Beach, Orange County, CA. 10-12-08. Copyright: Peter J. Bryant (pjbryant@uci.edu). Contact for originals
Adult female. Boat Road, Laguna Beach, Orange County, CA. 10-12-08.
Copyright: Peter J. Bryant (pjbryant@uci.edu). Contact for originals