There are five species of black widow spiders in North America, north of Mexico. The species found in British Columbia is the western black widow spider. This species of cobweb spider, or comb-footed spider, is found from southern Saskatchewan, Alberta and British Columbia south into Mexico. In British Columbia, it is widespread in southern BC and is most commonly found under objects in hot, dry localities. The look-alike false black widow spider (
Steatoda grossa) is widespread throughout the province. It may be mistaken for the black widow, but lacks the red hour-glass on its abdomen. In coastal British Columbia, the western black widow is often found naturally co-occuring with two introduced species of European house spiders: the giant house spider,
Tegenaria duellica and the hobo spider,
Tegenaria agrestis (Araneae: Agelenidae). Research in BC has shown that populations of western black widows are socially organized – immature and other females band together to improve their prey foraging success while mated, mature females disperse to rear their egg cases in private (Salomon et al. 2010).
Black widow spider venom is potentially dangerous to humans but these spiders are not aggressive and bites to humans are exceedingly rare, even in places where widow spiders are abundant. A variety of medical conditions are often misdiagnosed as being the result of spider bites. For appropriate and effective treatment, it is important that symptoms be accurately diagnosed. Read the article in Canadian Family Physician by Robb Bennett and Rick Vetter on the misdiagnosis of spider bites in Canada. For a review of the medical mythology associated with spider bites, read the article in Lancet by Geoffroy Isbister (2004). For excellent information regarding those "mystery bites and itches" that are commonly mistaken for spider bites, read this article.
Author: Robb Bennett, Research Associate, Royal BC Museum
