Halloween is for celebrating the scary: imaginary monsters—ghouls, goblins and ghosts—along with real but scary-seeming creatures such as bats, black cats and spiders. …Although spiders are common houseguests year-round, during October they finally get their due, although it’s not necessarily favorable. With over 47,000 described species, around 3,400 of which live in North America, most Americans have spiders as roommates whether they like it or not. …These arachnids (part of phylum Arthropoda) eat billions of insects yearly—mosquitoes, for example. …Fortunately, spiders want nothing to do with humans. Over the last hundreds of millions of years of their evolution they’ve never once shown a propensity to take a blood meal from us, unlike ticks.