Heather McDougal, who writes about curiosities and wonders of nature on her blog Cabinet of Wonders, has a good essay about black widow spiders, which have infested her new trailer.
Unlike brown recluse spiders, whose venom is cytotoxic, meaning it is meant to slow down the prey, partially digesting the tissues and making for failure of the prey’s systems, the black widow spider’s venom is based on a neurotoxin, which I would much prefer. In mammals, when they are bitten by a spider with cytotoxic venom, it means the tissue surrounding the bite turns necrotic (dies) and is often unable to heal afterwards. There are some truly horrific pictures on the Internet of brown recluse spider bites several months on, which I would rather not contemplate. The venom of a black widow, being a neurotoxin, has a more widespread effect, entering the bloodstream and being deposited at the nerve endings where the endings insert into the muscles. This causes intense, painful cramping and muscle spasms, and is very painful. It lasts a few days and then disperses, leaving only a few minor symptoms – spasms, tingling, nervousness and weakness – to remember her by. For me – though I would not want to encounter a black widow bite – the biggest fear has been for my children, because the smaller the body mass, the more likely the venom is to cause shock to the system and death.
Heather McDougal on black widow spiders