Discount supermarket chain Aldi removed its entire stock of grapes from the shelves of its Milwaukee, Wisconsin, stores in early November, after a shopper found a black widow spider in a container. The red grapes in that incident were purchased from Aldi’s Wauwatosa, WI, branch, and other black widow sightings have been reported at grocery stores in Michigan, Missouri and Minnesota, in recent months.

The black widow spider is a venomous species of the genus Latrodectus. The spiders are known for their striking red and black markings, and for the practice of the female sometimes eating the male soon after mating. Their venom in neurotoxic, and seldomly fatal to humans, though children and the elderly are more susceptible.

A few days prior to the latest incident in Wisconsin, a Michigan couple found a live spider in a bag of red grapes purchased in Brighton. In St. Louis, two more black widows were found in red grape containers in early October. In Minnesota, a spider was found in a crate of grapes at a school in Maplewood.

Aldi has pledged to use additional inspection procedures to help prevent any future spider incidents.

Black widows aren’t aggressive by nature, though will bite if cornered. One shouldn’t handle the spiders, and the best thing to do is to trap them in some sort of container, and move them outside.

The practice of using the spiders on farms in place of pesticides might explain their appearances in grocery stores, as of late. A decade ago, customers had complained about finding black widows in bundles of grapes purchased at Tesco supermarkets in the United Kingdom. A grape farmer later admitted to purposely using the black widows to control pests.

Incidentally, the UK has recently had its own problem with a widow spider of the “false” variety, after an infestation of the species shut down a school. Though, English false widows, of the genus Steatoda, are far less harmful to humans than the famous black widow of the Americas. Some members of the false widow genus can inflict bites which are medically significant in humans, though they generally don’t have any long-lasting effects.

Symptoms of black widow bites are a bit more pronounced, and typically include fever and swelling. Victims should apply ice to the bite, and also consult with a doctor to obtain anti-venom.

Image via Wikimedia Commons.