[lowbridge]

Excerpted: http://www.nydailynews.com/news/national/2010/10/04/2010-10-04_black_widow_spiders_infest_san_diego_elementary_school.html

[AnglePark]

We’ve had more around our house this year, here in Virginia. My girlfriend found one the other day, on the porch, that was freakin’ huge.

[camerongood210]

I saw my first and only black widow about 2 years ago. I’ve always wondered how dangerous they are. I would agree about the brown recluse thing. Those guys are something serious.

[meadsjn]

If the building was idle during the summer, the water in some of the gooseneck traps could have evaporated, and allowed critters to crawl in from the sewer pipes.

Usually it's the cockroaches that enter a long-vacant apartment, then spread to infest the whole neighborhood. Black Widows thrive wherever there are lots of flies, so that could be the source.