Like many of the best sci-fi thrillers of the post-A-bomb era, Eight Legged Freaks blames the mutant huge-osity of the spiders that overrun a Southwestern mining town on man-made evil, in this case a chemical spill. Like many of the worst pop-referential parodies of the post-''Scream'' era, this one stalls on laughs once the big joke has been established: A citizenry raised on movies like ''Them!'' and ''Tarantula'' is the toughest to convince that there really are outsize arachnids in town.
The usual character types assemble. David Arquette assumes his ''Scream''-ingly familiar attitude of ironic doofus sincerity as a mining engineer, Kari Wuhrer (''Anaconda'') is the savvy local sheriff, and ''Ghost World'''s Scarlett Johansson plays the sheriff's pouty daughter. The thankless role of black guy in a white burg who spouts Don't-Trust-the-Man conspiracy theories but can't see a 10-foot bug right in front of him falls to Doug E. Doug.