Bug.

About Bug

Bug is a 2006 psychological horror film directed by William Friedkin and written by Tracy Letts, and starring Ashley Judd, Michael Shannon, Lynn Collins, Brían F. O'Byrne, and Harry Connick Jr. Letts adapted the screenplay from his 1996 play of the same name. It follows an isolated woman living in a rural Oklahoma motel who spirals into psychosis after taking in a mysterious Gulf War veteran.