By October 1998, Umbrella had collected much data on arachnid reactions to the T-virus from the series of incidents which took place in and around Raccoon City that year. With the Latrodectus genus ("widow spiders") possessing a much stronger venom in comparison to the tarantula spiders seen in Raccoon City, they were selected as prime test examples.
The Black Widows were already being developed by Umbrella by December 1998; the company had plans to distribute them to a number of their facilities via the transport terminal in the Antarctic Base.
During the Antarctic outbreak of the T-virus, the Black Widows being transported took advantage of the emergency to break out of their crates and settle around the facility.
Like many spiders, the Black Widow possessed four pairs of legs attached to its cephalothorax, connected to the opisthosoma (abdomen) by a thin section. The Black Widow's appearance was disambiguated from other spider-based B.O.W.s by its complete lack of body hair. Like other spiders, the Black Widows would release little spiders from their abdomen if killed. One of these spiders, like the Black Tiger, reacted differently to the T-virus than others of its kind and, again like the Black Tiger, reacted by growing significantly larger.