That ‘spider bite’? Blame it on something else

Q: Do spiders bite people out of fear, hunger or curiosity?

A: It is a misconception that spiders are habitually out to bite human beings. Spiders prefer to feed on invertebrates, often paralyzed with venom evolved for that purpose. Bites to humans, when they do occur, are most likely defensive.

Usually spiders are not even able to chomp on people, partly because the arachnids’ fangs are too small and weak. What victims take to be spider bites often are caused by something else entirely, like wasps, ants, bedbugs, an infection — or even thorn pricks.

The brown recluse is one of the few species capable of a harmful, tissue-killing bite. But after reviewing case reports, Canadian researchers found that in no instance has a brown recluse actually been caught in the act of biting; none was captured or identified afterward.

Despite the persistent diagnoses, the scientists noted, brown recluse spiders are not even found in Canada.

“Even if brown recluse spiders occasionally found their way into Canada, the statistical probability of people being bitten by immigrant spiders is effectively zero,” the study concluded.

In a review article in The New England Journal of Medicine in 2005, the authors also found that many reports of brown recluse spider bites in humans were poorly supported by evidence.