Black Widow Spiders and Toronto: No Need to Panic

photo credit: snowboard4bradley

On July 22nd, 2009, The Toronto Star reported that two Northern Black Widow spiders (Latrodectus variolus) have been found in the GTA within the last year. This shouldn’t be news, as the article itself outlines that these spiders have been found throughout Ontario over the “past decades” but the reporting in the Star bordered on sensationalism (the spider is described at one point as “this fabled doyenne of death”) and, in my opinion, irresponsibly overstates the risk of the spider to those that live in the GTA.

Here’s what the article should have said:

If you live in the GTA, be aware that a female Black Widow Spider might be in a web underneath your discarded bits of wood from your deck-building project. But temper that knowledge with the fact that she’ll likely not bite you. If she does, she’s doing it in defense and while it the bite will hurt, odds say you’ll be just fine after a visit to a doctor.

So, do we need to worry about Black Widow Spiders? In a word, no. Here’s why:

1. Black Widow Spiders are not aggressive. The spider will only bite as a last, defensive resort. This would likely be due to a human unknowingly placing a hand on the spider. Why unknowingly? Because:
2. Black Widow Spiders are often found in out-of-the way places. Think corners of cupboards, under the pile of wood in the garage (they do like to hang out in outhouses, which is more of an issue in cottage country, not the GTA).
3. The Black Widow’s venom is a neurotoxin. This means it does not kill flesh, resulting in necrosis. It hurts like a sonofabitch, yes, but the bite will not lead to sepsis and the associated concerns of a systemic bacterial infection.
4. Mortality rate is less than 1%. If bitten by a Black Widow Spider your likelihood of dying from the bite is equivalent to your lifetime risk of dying in a car crash. For most of us, the likelihood of driving in a car is much greater than the likelihood of getting bitten by a Black Widow spider.

The Star article’s tone was alarmist by suggesting that we’re in some kind of deficit situation due to the lack of anti-venom:

Anti-venom is available in this country, but is in very sparse supply, says Dr. Margaret Thompson, medical director of the Ontario Poison Centre. “There might be two vials of it in Canada.”

Let me say that the reason that there is such little anti-venom in the country has to do with the fact that it’s not what is first used in the treatment of bites. It is true that kids, the elderly and the immunocompromised are at a greater risk of suffering severe symptoms of Latrodectism, the clinical name of a Black Widow Spider bite, but most outcomes from treatment for bites are positive and without the need for hospitalization, let alone anti-venom.

On-line, people seem to have reacted in the same tone as the article.

Case in point, commenters on the Star’s article are suggesting that the presence of these spiders is reason enough to bring back cosmetic pesticide use:

We need to bring back pesticides especially considering the fact the summer is so mild, not enough heat to burn anything off, not enough winter to kill things there now either. I for one will be using it regardless.

The use of 300 cosmetic pesticides has been banned in the Province of Ontario since April 2009. I’ll highlight the term cosmetic, aka pesticide use for looks only. If we do, perchance, happen to become overrun with Black Widow spiders, it will no doubt be considered a public health concern and pesticides will be used in eradicating the spiders. Just to reiterate: pesticides have not been banned outright in the Province and the presence of Black Widow spiders is not reason enough to bring back their use to make your lawn look nice.